"With Gaddafi's heavy machine guns it was possible to shoot down a helicopter, as the terrorists' own footage of 1988 shows. This is what the security forces feared most. It may have been a lucky hit, but for the army and crew, once was enough. No one died in this attack, but there were many other deadly arms to fear."
Apparently ITV has real footage and somehow replaced it with a youtube video. ITV said:
"The events featured in Exposure: Gaddafi and the IRA were genuine but it would appear that during the editing process the correct clip of the 1988 incident was not selected and other footage was mistakenly included in the film by producers." (http://www.bbc.co.uk/news/uk-northern-ireland-15082177)
You can watch the segment http://www.youtube.com/watch?v=h6r-kNct630, or the full documentary http://www.itv.com/itvplayer/video/?Filter=276162.
Found by a http://forums.bistudio.com/showthread.php?p=2028287
