When 7FLIX first started I found Add Skip didn't work because it used MPEG4, it does now.
What changed?
Will Add Skip now work on the other MPEG4 channels?
It sounds like whatever stopped ad skip from working on the mpeg-4 channels was not that they were mpeg-4 but some other parameter within the recordings of the mpeg-4 channels. The type of audio maybe.
Maybe 7flix have changed something that makes that channel's recording suitable for processing the ad skip. This is actually good because 7flix was the one mpeg-4 channel that did not also broadcast an mpeg-2 version.
The way to find out if 7HD, 9HD and TenHD now work would be to record them and see what happens. I can't do that at the moment so I'll leave it to someone else to try.