I don't delete things. I consider them all memories. My first 5 vlogs were the most horrible things ever, but they're still up. I'd regret it if I took anything down. It's nice to be able to go back and watch things and remember, even if it's just remembering how horrible I used to be at vlogging and reminding myself of how much progress I've made and how much I've learned since then.
I've put a good 4 or so videos I wasn't happy with to private viewing instead of deleting.
That way I can always reflect on them and see how far I've progressed.