Well, that was actually an old video of years ago. Andreas has made many many more and when watching all in chronological order you see his stance is developing as well by the booming developers world. I see lab work in alts, but most innovation is still done around Bitcoin itself (side-chains, second-layer things). But in case of Segwit, it were the alt-coins which implemented it first (while invented by a Bitcoin developer). So they functioned indeed as test-lab. Also the work in anonymity improvements and better Proof-of-work algorithms (POS for instance) is done first in alt-coins. It's just to risky to implement something unproven into a $250 billion blockchain without testing it thoroughly. The core-devs are very conservative (which is a good thing).