Can a video used as evidence be viewed by outside people not involved in the case

You don't indicate whether this was a civil or criminal case, but I'm not sure that matters.  You also don't indicate what the video was, i.e. whether it was something which is required to be kept confidential, such as video of a medical procedure.  In general, there is no reason why evidence in a litigaiton cannot be viewed by the public.  If there is evidence that one party believes should be kept confidential, that party would ask the court to seal it.  If the evidence is not required to be kept confidential, and there is no court order sealing it, there is generally no reason why it can't be viewed by anyone.