Here's a site where you can watch amazing CS:S movies.
https://www.sourceradio.com/
As a guest you can only watch them in low definition but you can register or use this account to access high definition
Login: gamezone24
Password: gzcss
Please don't change login infos and email we're not kids... Let the community enjoy the stuff. Anyway you can always make your own registration
To watch movies you must click on Movie Vault in the menu bar. I suggest you sort the results by User Ratings
Warning : You need a good computer to watch movies in HD but it's worth it, if your processor can't handle it just log out and try watching the movie in LD instead. If it's still doesn't work you can also download some movies from the download section of the site.