Rod balance is important in fishing and not in casting.
That is why the French nymphing DVD says to balance the outfit with a heavy reel. This results in an outfit that is tip-light/butt-heavy when the line/leader system is out. You don't need to force a tip heavy rod/reel into a tip up position for fishing.
The outfit may be heavier over all, but you are not fighting the natural balance of the rod/reel to keep it tip up during fishing.
The rod/reel/line should be balanced for the type of fishing you do with the amount of line you would normally have out. If you mainly fish streamers from a boat as musky fly fishers do in the USA, you want a tip heavy set up.
If you keep your rod level most of the time or do all kinds of fishing so the rod angle varies, you want a neutral balance point with the nominal amount of line out of the rod tip.
One can also adjust the balance point by holding the rod higher or lower on the rod grip once the cast has been made to account for the amount of fly line out.
Whenever the question of rod and reel "balance" is raised, there are those who will maintain that the reel balances the rod during the cast. This is a carry over from spin and casting rods and reels where the line weighs virtually nothing AND the cast is always made when the line has been wound all the way in. So in spin and casting rods a reels the amount of line and the weight of the combined line and reel is fixed. Regardless of the length of the cast, the rod and reel has a fixed balance point.
This is not so with fly casting. The amount of line varies during the cast and the length of line that is cast will vary from cast to cast. In addition, when we pick up line and recast , we do not start with all the line back on the reel. Indeed, it is advantageous to begin with some line out of the rod tip. So the balance point is not fixed but varies throughout the cast.
Secondly, there is the mistaken belief that a "balanced" fly casting outfit will somehow allow us to cast further and more effectively. This is not true. In reality, a rod without a reel with the line lying loosely on the ground is the most efficient way to cast. The reason is that the reel and line held on the reel contribute nothing to the cast. They actually hinder the cast by adding mass to the casting system that has to be accelerated and decelerated during the cast.
If the cast were made like a teeter totter with a pivoting of rod at the balance point, I can see the need for the counter weight of the reel. But that is not how a cast is made. The power stroke of the cast is made with the wrist locked and not with the rod pivoting like a windshield wiper.
Charles Ritz wrote in A Fly Fisher's Life (1959):
Fly Angler's OnLine "Bamboo Rods Part 29"
"Before describing my methods of examining rods, here are a few considerations I believe to be of importance.
Let us first rid ourselves of a widespread idea, which I have often had occassion to point out as false or, at least, much exaggerated: the reel does not balance the rod; though in the past when rods were ten feet or more, very long and heavy, a reel as a counterweight did produce the illusion of balancing the rod in the hand; but it is the line which plays the principal role owing to its weight and the shape of its taper. It is, indeed, on the line that the rod depends above all for giving its maximum, and yet retaining its balance. The ideal would be to be able to fish with the reel in your pocket."
Vincent C. Marinaro wrote the following about rod balance, "In the Ring of the Rise," Crown Publishers, Inc., New York, copyright 1976, pp. 39-41.
"BALANCING A FLY ROD
In 1889 R. C. Leonard, a tournament caster, stepped to the platform without a reel on his rod and simply coiled the line at his feet. With that abbreviated rig he proceeded to smash all existing distance records, including his own, by a wide margin. It was a shocking thing to competitors and spectators alike. It was a momentous discovery from which not only tournament casters but fishermen as well should have profited. That early-day pioneer discovered an extremely important principle in rod dynamics. It amounts to this: That the caster must move the useless weight below the hand as well as the useful weight above the hand; that the removal of dead weight below the hand helped to overcome inertia more quickly, increasing the tip speed, thus imparting a greater velocity to the projectile or fly line. It should have been a valuable lesson to everyone, but it wasn’t. It remained only among the tournament casters for many years.
If you examine the books and catalogs of those early days you will discover that manufacturers and fishermen-writers discussed very learnedly and extensively such things as “fulcrum point,” “counterpoise,” “balancing the fly rod,” and “letting the rod do the work,” none of which has any merit whatsoever. Not until very recently has there been an awareness of this valid principle. It is evidenced by the availability of numerous fine, very lightweight reels on the market today. In view of this trend I should not be discussing this subject at all, except for the fact that I am frequently surprised by the comments of writers and the recommendations of suppliers or manufacturers prescribing a specific size and weight of reel to balance a particular rod. There can be no such thing as balance in a fly rod. There can never be a fixed “fulcrum point.” Every inch that the cast is lengthened or shortened changes the alleged balance and every unnecessary ounce in an unnecessarily heavy reel dampens and degrades the cast. If you wish to explore this a little further, you can try an experiment as I did some years ago. If you have or can borrow enough reels, let us say in two-ounce increments, all the way from the lightest, about two ounces, to something about eight or nine ounces, you will have enough to make the experiment. Use the same weight of line on the same rod for all trials. With the lightest reels the casts are sharply and cleanly delivered flat out with enough velocity to turn over the leaders. You also get a tighter front bow if you want it. As the reels get heavier there is a noticeable lagging in the forward loop until finally with the heaviest reel there is decided dropping of the loop, and probably a failure to turn over the leader properly. This effect is most pronounced on long casts. And consider how much worse it could be with those reels that were manufactured with a hollow arbor into which the purchaser was urged to pour lead pellets through a little trapdoor in order to correct the balance of his fly rod!
You can suit yourself about these matters but for me there is only one sound system and that is: Use the lightest possible reel of good quality and adequate capacity no matter how long or heavy the rod may be . . . ."
As both Ritz and Marinaro state, if you remove the reel and place it on the ground and cast just with the rod and line, it is much easier to cast. I have done that and I agree with Ritz and Marinaro, the reel is not needed to balance the rod for casting. The feel of the cast is actually the line causing the rod to bend. It is the moving line outside the rod that "balances" or provides the dynamic resistance that causes the rod to bend.
I realize that there will be those that will not believe Charles Ritz or what I have written. You owe it to yourself to try casting with the reel on the ground as I did.