I don't know if the first sketch used any input from the video, but it definitely was not based 100% from it. There were human witnesses who contributed to the first-shared composite sketch.
We know this because when lead investigator Sgt. Holeman appeared with the victims' families at CrimeCon in 2018 (this was prior to the "new" or young BG sketch being released), he did a panel with reporter Ashleigh Banfield where he described how that original "old" BG composite sketch was developed:
Banfield: But there were witnesses if I’m not mistaken who were able to lend information that got you to the sketch
[Sergeant Holeman nods affirmatively]. Can you tell me a little bit about the witnesses? Where did they come from, what did they see?
Holeman: I don’t want to go into great detail, but they were near or on the trail....Again, it takes a lot of time. I’m not a sketch artist. The FBI actually–an agent from the FBI–did the sketch. And you know,
I think when somebody sketches it takes like, 10 minutes [shakes head ‘no’]. It takes several
weeks. But to get the information, to find the people that we believe saw that person that day near the time of the murders, that takes months. So we had to locate these people, interview them, find out who they really saw. Did they really see the guy on the bridge from the video, or did they see Mike out there helping search, or did they see somebody else out there helping with the search? So we had to identify those people, and once we felt like we identified the people that actually saw the guy on the bridge, then the sketch itself took, again, several weeks. They sketched it, looked at it, “No…that’s not correct”. I will say that she still–[
Clarification note: he quickly corrects his use of ‘she’ to ‘they’]—they, there’s a couple people— still aren’t convinced that’s the proper hat, but that’s the hat that the sketch artist could come up with as close to what the witnesses were describing.
The source for this transcript of the CrimeCon interview is:
Delphi Murders CrimeCon Interview Transcript - CrimeLights