Many of the comments to this video illustrate the popular myths that caused this film to be made in the first place.
As with any machine gun, their effectiveness was (and is) more a factor of gunnery skills than rate of fire and raw volume. Fires that are poorly directed fail to suppress and can never hit. Increasing the rate of fire or volume does not fix this.
The lesson of this admittedly propaganda-based film is NOT that German full autos are ineffective, rather, it correctly points out that the German gun’s faster cyclic rate does not convey greater effectiveness.
Against ground-based targets, any fully automatic firearm has more than fast enough cyclic rate to be effective as a machine gun. Good machine gun gunnery dictates that most bursts will run around 6-9 rounds. Consider that a plodding cyclic rate of 360 rounds per minute works out to six rounds per second and even “slow” cyclic rates are faster than this. This sends a complete burst within a second or so. A few tenths of second or a few more or less rounds per burst won’t matter. Of course, the lower rate of fire is likely easier to control, the cone of fire is probably tighter, and ammunition at belt fed quantities quickly becomes heavy.
The real solution to determining the best approach is to do something demonstrated in this video. Test the equipment, technique, and doctrine. Try whatever you like, but keep track of where the bullets actually end up and how long it took to get them there. If a given technique, doctrine, or equipment is truly more effective it will show up in an appropriate measured test.
Rumors among Allied troops caused many myths of the German MG 34/42 to spread and it’s unusually high rate of fire and subsequent distinctive firing signature. The German gun was effective but that was due more to the skill of Germany gunnery, as forcibly demonstrated at the Battle of the Somme in World War I, and was not due to any magic in the gun or in a higher rate of fire..