Hi.  The short answer is that I have no idea.  The history of the Arpanet and early Internet is well documented and they could have used any of a lot of sources.  The photo at 7:35 is a bunch of the programmers standing around one of the first IMPs at BBN, as you can see here:

https://www.livinginternet.com/i/ii_imp.htm

The rest look to me like stock footage.

Regards,
John Levine,