Some engineers wrote a couple of insightful internal post-mortems about Google Video after the YouTube acquisition. It's telling, I think, that the deep analysis of what went wrong came from front-line engineers rather than the executives you'd be expecting to produce it as part of their job. I read them many years ago so what follows might be a bit garbled by time and bad memory, but the gist of it went like this:
1. YouTube bet on user generated content. One of Wojcicki's primary decisions was to focus on commercial high-end content by trying to cut deals with firms like Disney.
2. YouTube bet on Flash Video. Google Video used a VLC-based browser plugin that never worked as well and didn't have as much distribution. This was partly driven by the first decision, because Flash didn't support the video DRM that movie houses wanted, and was optimised for small low bandwidth, "postage stamp" sized video instead of high-def full screen that commercial content wanted. YouTube had no formal strategy around commercial content beyond turning a blind eye towards the piracy on their platform, that let them outsource their video tech to Macromedia, who were quite good at it.
3. YouTube bet on social. They had comments, thumbs up, thumbs down, channels and other social features when Google Video was still a search engine badly welded to a video store. Google didn't "get" social at that time and GV/Wojcicki saw it as a net negative anyway because does Disney really want their premium content to be shown next to a bunch of inane comments from anonymous trolls?
4. YouTube was implemented in Python. Google Video was implemented in C++. Python allowed the YT guys to iterate way faster and throw features out the door way faster, at a cost in performance and reliability. But a social website doesn't really need much reliability and whilst the performance costs were killing them, Google bailed them out after the purchase by rewriting and porting large parts of their stack to their in house tech.
I think those were the main problems identified in the post-mortems.
What's interesting is that of course the general themes here are identical to what is causing YouTube problems now. Wojcicki was obsessed with professional/authoritative content. It killed Google Video then because there was a competitor who bet on the little guy, but now she controls that competitor she's doing it all over again. YT is actively suppressing the little guys in favour of big media, they've added a video store, their recommendations aren't social anymore but rather just promoting whatever political elites are saying today, she's removing other social features like downvotes, etc etc. She never learned anything from her prior failure, and why would she? When Vic G failed at Google+ he was immediately fired, but Wojcicki cannot be penalised for failure. Whether that's due to her familial connections, her gender or what is hard to say, but the contrast between her and what happened to other execs that failed to beat their competition is hard not to notice.