So in this particular case, a family member shared it during post-sentencing impact statements. This is after the jury has rendered their decision, and it is up to the judge to decide how severe the sentence should be.

Family can read fictional poems, personal thoughts, videos or photo montages. They can put up a picture of the deceased, and make statements like if "Bob was here, he would say x, y, and z"

The point is to influence the sentence.

Provided that the family was very clear this was not historic video, and I think it was, then one can see how this isn't obviously out of bounds