A valid source has to be all of the following: original, primary, and direct.
The celebrity’s social media accounts are a primary source.
News sites can be a primary source if their content is original, such as an interview with the celebrity. If the news site is referencing another source, then it’s not original. It’s secondary.
Can a YouTube video showing the celebrity be a source?
Yes, a video provides a strong proof of the Fact. However, it needs to be possible to understand the context of the video. There are compilation videos out there where the context is not clear. Those can’t be accepted.
Is Wikipedia a source?
No, a source needs to be direct. Wikipedia has no original content. It’s only references to other original sources.
In rare cases we accept a second hand source. For example, say a celebrity said something on The Bill Maher show on HBO. That show is copyrighted and has limited redistribution, so we might not be able to link to it directly. However, another reputable source may have reported on it. In this case we can use the source which reported on the show, even though it would be considered a 2nd hand source.
So when the primary source is behind a paywall, we accept a 2nd hand source.
Sometimes the original source is dead, like the blog of the celebrity is no longer online but it was reported on by a mainstream news outlet. In this case, we can accept the 2nd hand mainstream news outlet as the source.
Cetain content is posted on social media (such as Snapchat) cannot be linked outside the app. In that case, a reputable mainstream news source reporting on the celebrity’s post can be submitted.