The 5th Amendment covers the right to not have to self-incriminate in the courtroom or anywhere. If you plead the 5th during a border search, however, it essentially means that you are likely to commit criminal activity but don't have to admit to it.

You are probably thinking more of the fourth amendment, which supposedly protects against unlawful search and seizure - including information about your whereabouts, etc.

Also, I probably wouldn't use a YouTube lawyer as my sole reference for doing that sort of thing, just FYI.