vit05 answered it, but I want to give you more detailed steps.
This one might helpful for your interests.
Guideline on posting images, hyperlinks (by tbct_mt2)
In a nutshell, in order to post videos inside your posts.
There is only one way, by posting link to videsos inside image, like this:
Additionally, you can adjust image size by using the option width=interest size, like this
[img width=interest size]http://[/img]
Or, centering images with the option in order to make a better appaerance of your posts.
Doing this, others have to click on attached images to visit videos' links and watch them.
Why?
Simply leaving a short note below the image, then everyone will know it is link to video and they have to click on the range to watch it.
You should also include additional descriptions as it's leading people away from the bitcointalk landing page.