The above link looked like the whole interview. Had I known all the Fleetwood Mac material would later be posted in a single video, I would have waited to post that instead.
In additon to the above, there is only another 67 seconds (two fan questions):
https://www.youtube.com/watch?v=zL4S5XtgkKk
The fan questions run from 2:04 to 3:11. The entire discussion of Fleetwood Mac (including the above) runs from 0:39 to 3:11.
Transcript of the new material (fan questions):
1. Question on his overall thoughts of his tenure in Fleetwood Mac:
Mason: "We were the Fleetwood Mac cover band."
interviewer: "Well Mick had said he didn't have a problem with you all coming out [on the road]. From his perspective looking back, Mick had said, 'We should have called it something else.'"
(As it was, they sold poorly and had to play as an opening act. Had they called it something else, would they have even been booked?)
Mason: "You know what? The real problem is that Christine did the album, but she wouldn't go out on the road."
interviewer: "Yeah."
Mason: "I mean that would have been a huge difference if she had [gone] out there. But she wouldn't do the touring with us. But she did the album. So, you know, it was a little odd."
2. Question on whether he was considered to replace Bob Welch.
Mason: "I have no idea."
interviewer: "So back then, when Bob Welch left, Mick never approached you? Way back then? It would have been in '75 – '74-75."
Mason: "No, no."
(Unlike Lindsey Buckingham, in 1974 Mason was bigger than Fleetwood Mac. He would have been foolish to join. It was only reluctantly that Lindsey joined.)