This tool by Power Ad Spy claims to let you go through the complete ad campaign history of your competitors, see their tags, see the engagement, etc. I don't know if it's any good as I haven't used it personally but it has a trial. Looks like to get the Youtube data it ends up being $150 a month, but maybe you can scrape up everything you need with the trial (100 searches / 1000 ads for 10 days).