I must agree with Mook on this point, though I admit that I'm no expert on the Bart Cham Dao. In my WT lineage it is basically a master's level form, and not taught publicly. But, I have witnessed various versions of this form performed by several WC and WT masters of reputable Yip Man lineages, and none of them look anything like the form William Cheung demonstrates here. Mook is very diplomatic. I don't wish to offend anybody either, but I honestly doubt that the form William Cheung demonstrates in this videoclip comes from GGM Yip, or from any other old and established lineage. I suspect it is almost entirely a creation of William Cheung himself. Beyond that, I will not hazard any opinion.
Oh, and regarding jumping--I'd say it would be most unusual in the WC/WT that I've seen. It seems to contradict the general emphasis on rooted stance and sound structure. However, there's an exception to every rule. And if you have a fertile enough imagination, I'm certain you can envision situations in which you would have to jump. For example, I once worked in a foundry. What if I got in a fight with a co-worker and we overturned the red-hot crucible and spilled molten bronze all over the floor? Or if we suddenly found ourselves sparring in the middle of a swarm of flesh-eating scorpions? With these and other likely scenarios in mind, remember, "Never say never!"
