A lot of the points that they make in the video are just flaws with Facebook's implementation of the app, rather than being a point for HTML5 or a point against native.
Truth is - HTML5 apps can be made to perform well but there are limits. Battery life suffers and you may find in future that the cool animation/whatever you wanted to add in is too laggy (especially on older devices).
Older devices will slowly dissipate from the market because of the ubiquitous two-year contracts, though, and eventually everyone's phones will be capable of delivering native-like performance on HTML5 apps. It's only a matter of time.
Doubled from awesome to... awesome? Native performance is the goal. I don't see how much better a data heavy native app like FB can get, but I do see how HTML5 apps can get better.
Really? If anything I would have thought that HTML5 was more battery efficient- there's only so much you can do with it, after all.
I spent a long time optimising a mobile webapp I was working on and while it was 95% there, that last 5% bugged me to no end. So I investigated native options. But I learnt to avoid mixing CSS3 box-shadows with transition animations and that sort of thing- you definitely suffer in FPS.
Of course native is more efficient - it takes fewer CPU cycles to get what you want done. Now you're right that as a result you might be more likely to include animations and effects etc which will drain more power, but that's a choice you can make.
Truth is - HTML5 apps can be made to perform well but there are limits. Battery life suffers and you may find in future that the cool animation/whatever you wanted to add in is too laggy (especially on older devices).