Is it legal to be tipping over this much making the robot over 36 inches for a split second like in this video? (at 34 seconds)
Or will the 36 inch limit be strictly enforced? (DQ for going outside it even for 1 second)
If your robot tips which makes it go out of the horizontal size limit, you will be in violation of that rule. If it’s match affecting, then you will get disqualified. If it isn’t match affecting or you tip back as soon as possible, then there’s a chance you won’t get disqualified. It’s rather more of the judges discretion if you should or shouldn’t get disqualified. Probably if it’s repeated over and over every round you may get disqualified as well.
Hopefully this helps 
- [TVA] Delta III
As seen in the post here, if it is not match affecting, you get a warning. If it is ruled as match affecting, then it will likely be a disqualification.
To add on, if you are doing it repeatedly (for instance, every time you deploy) , you will get DQ’d.
According to this Q&A answer, it is correct to say that the 36 inch maximum size is determined by:
(Emphasis mine.)
Thus, most correctly-sized robots should fit within a vertical cylinder of 36 inches in diameter, except in a few cases, such as the one shown in this illustration from that same Q&A answer:
The rule is mostly the same as it was before; the main reason for the change was to make size inspection easier and more consistent.
On the other hand, according to @Highwayman’s summary of day two of the EP Summit webcast:
I have not yet seen anything elsewhere to confirm this, but I will likely ask about it soon in the Q&A.
EDIT: I have now asked about it in the Q&A, here.
You are correct, and most of what I wrote above is incorrect. I believe I will edit my previous post to near non-existence so that nobody will mistake wordiness for correctness.
It’s probably worth asking.