It makes more sense if you think about how 2006 looked like:
- the only way to money in 2006 was advertising and the idea of advertising in internet videos was borderline crazy (remember when internet was tv but without ads?)
- it was just one of many potential interesting players. To think it could've been Vimeo, but the founders cared more about their main project: collegehumor
Now we know that was an excellent deal for Google (now Alphabet), despite being a long bet.
Good to have top security talent and good cloud security tooling if you're in a cloud play.