I have never heard anything like "plain", I think they meant "point" but didn't enunciate well.

No, the word "plain" is never used that way, but his pronunciation may have been careless. If you want a real answer, see if you can find and post a link to the youtube video. Depending on the word following "point," it would be easy, in sloppy speech, to omit the "t" and say something like "seven poin' nine," for example. 3.9 in US English would always be read as "three point nine." 7.0 might be read as either "seven point oh" or "seven point zero." I'd say "seven point oh" most of the time, but if I wanted to be sure I was understood--over the phone, or dictating to somebody--I would probably say "seven point zero."

it may have been the reviewers clumsy own personal way of saying "70" seven zero. the plain was to possibly emphases it was not 7.0 or 70.00 Although seven zero (a less common way of saying seventy).

7 (point) 0 3 (point) 9