Sorry kookabat, I hadn't realised that you are an eyewitness to this particular aircraft, and a highly motivated one at that it seems! Reading your post, you say that:
I do remember the aerial going from the tail to the mast near the cockpit and then going out to a wingtip on this particular aircraft
So have Danny and I been looking in the wrong place? Did the wire aerial arrays describe a "T" looking down from above, all joining not at the fin, but at the radio mast? That would make a lot of sense, for the feed could then come down the mast as before, straight to the TA-12 transmitter. The wingtip/mast/wingtip aerial being an efficient (though directional) dipole array.
Danny as to why the Australian aircraft should have been so fitted, could they have been intended for use over the sea? I'm thinking of the Coral and Arafura Seas in particular, from where came the threat of invasion, and to where the offensive to drive back the Japanese would be taken. Such operations would have required longer range comms for which MF alone would not suffice. What do you think?
As to why the IAF should apparently have had the same fit, I agree it doesn't add up at first glance. Of course, we don't know when the YouTube clips were taken. Is it possible that they were later deliveries? Is it possible that they were initially for the RAAF, and hence so fitted, but diverted to the IAF from the very large Australian allocation?