So tittle says, like images, you need to use imgur, but for a video?

You need to upload it to YouTube
and then you take the link.
This is how you do it, for example, for this link
http://www.youtube.com/watch?v=yQOdiTny2Vk
You take the yQOdiTny2Vk, and the put it in the bbcode like this.

[YOUTUBE]yQOdiTny2Vk[/YOUTUBE]

For spoiler it should be like

[SPOILER="This"][YOUTUBE]yQOdiTny2Vk[/YOUTUBE][/SPOILER]

Answered and closed.