I am assuming you aren't advocating that it's OK to take bad shots as long as your shooting a heavier arrow
Your assumption is correct. Point is, wild animals are not McKenzie targets. They are unpredictable and can move unexpectedly. In the split second of time between it takes for you to decide to commit to the release and for the arrow to leave the bow, what began as a perfect setup on a broadside shot COULD turn into a severe angling shot. I've even seen it happen with a rifle, so it don't bother trying to insult my intelligence by saying a fast arrow will prevent that kind of thing.
I personally prefer to shoot in the upper 70's of KE just for those murphy type cases.
Well, duh! You HAVE to. Know why? You have to speed up those light arrows and generate all that energy just to match the amount of MOMENTUM I get with my big ol' logs out of a puny 50 pound recurve. Light arrows work if, and only if, you can stand the draw weight and draw cycles it takes to get 'em moving fast enough to generate enough momentum to make them work. I don't like working that damn hard, so I get my momentum the easy way, with arrow weight.
About videos, I've seen all kinds of stuff on video. I was watching one just the other day where a guy shot a deer, arrow came to a dead stop in the rib cage and the deer ran off. Lo and behold! The guy climbs down outta his tree and walks over to where the deer was and says "There's my arrow. Lots of good sign on that arrow." Now that was quite a trick, seeing as how the deer ran off with the fletchings sticking out his side. Of course, he never picked up that arrow to show to the camera. That would've been an even better trick. LOL
And that's far from the first time I've seen such goings on with light arrows on video. I don't doubt the gal got her elk with a light arrow, but don't try and tell me it 'blew through'. They can't even get 'em to reliably blow through puny little deer on video. Watch a few kill shots in stop frame and you'll what I'm talking about.