Depends on what the video is and why it was removed.

If it was removed for copyright reasons you would have to go to the website the video originated from. (ie: movie trailers will appear on whichever studio made its web site)

If it was removed because it was a user-made video that broke their content guidelines such as it contained violence then it's just bad luck.

Search for the video on Google by describing it. Chances are it's been uploaded elsewhere.