There is a whole genre of youtube videos with AI generated Feynmann voice based on those lectures. They are of surprisingly high quality.
I presume the original videos of Feynman are lost, or never existed?
The Feynman Lectures website does have links to recordings of almost every lecture, but no video. BUT there are thousands of photos --- many photos of each lecture, showing Feynman's blackboards.
Also, there are videos there of a series of 7 lectures at Cornell in 1964.
I found this channel to be ok-ish.