Just in case you haven't seen this:
[Update — some people seem to be getting an error when they try to play the video above — you may have better luck with the one below:]
I associate this sort of thing, from long ago pre-internet days, with Ian Catford, who was able to do this for new phrases more or less on demand. My experience with his displays of this ability go back so far that the preferred way to demonstrate it was to play a reel-to-reel tape backwards.
And I'm not the only one with this memory of him: looking for a link to Ian on the web, I found this:
Ian is also famous for his amazing ability to repeat speech backwards. When asked about this, he reported that he started studying phonetics at the age of 14, and his phonetic skills helped him to gain a position with the BBC as a radio actor, starting when he was 17 – often speaking in multiple exotic dialects. Also, in a production of Alice Through the Looking Glass, he recorded ""Jabberwocky"" both forwards and in reverse. The BBC reversed his reverse performance and it came out quite intelligibly with an appropriate other-worldly quality.
Alas, the link is to Ian's obituary: he died on Oct. 6, a bit more than three weeks ago.
Requiescat in pace.