If an assault is captured on video, and charges are not filed right away, do normal statute of limitations apply?

Admissibility in court does not depend on the statute of limitations.  If the statute of limitations has passed on the assault charge, there can be no criminal charge of assault (it's not a question of admissiblity of evidence), but that doesn't mean tha evidence can't be used in other cases  If relevant and otherwise admissible, evidence can be admitted long after the statute of limitations on the behavior has passed.  You need to think about other questions.  For what purpose would the evidence of the assault be offered?  What type of evidence?  Can the evidence be authenticated?  Is it hearsay?  In what type of case?  If you're referring to a civil assault claim, the statute of limitations may well be different that the statute of limitations for charging a crime.  In any event, I'm not a Pennsylvania attorney and may be wrong, but I've never heard (outside of a novel) of the statute of limitations being affected by whether or not there was video evidence.