It's not 100% clear from their statements but my guess would be they are referring to UADFs.
Earlier on in the talk when discussing the hit on the F-35A they talked about the difficulty of the pilot getting a warning that a missile like Majid is headed for him if launched from perfect ambush position. If MAWS doesn't pick up the missile's IR signature (entirely possible depending on weather conditions) then it's very unlikely to get a warming due to missile being picked up by radar as it's a tube only a bit bigger than a MANPAD missile. If F-35A's own senser doesn't pick it up then it's equally unlikely for an AWAC to pick it up, and even if AWAC pick it up there isn't enough time to process the information and warn the pilot before the missile hit.
In the later conversation about CCA, in Ayi's description where he describes the CCA as having the signature of a surface-to-air missile he used the phrase "地导" (SAM) instead of "IR missile" which they've been using to describe Majid, so I'm guessing he had in his mind something like a Buk. The idea being although UADF are J-10 sized, they are VLO and smaller than other 5th gen fighters, even F-35 or the future Su-75 so they don't show up as an aircraft type target but rather something more like a missile even when viewed from an unfavourable angle by an AWAC.
