That Youtube video was of the Comair proving flight last year, not yesterday's one.
It's interesting that the Airlink flight (ZS-YAA) returned all the way to Johnannesburg direct without stopping in Windhoek, which is what it will do in service, I believe. (That's so that you can get a connection to Johannesburge or Cape Town.)
Also interesting (at least to me!) is that FR24 tracked the flights up to about 280 nautical miles away from the island, with the aircraft at 37000 ft. That's a pretty good range for the ADSB receiver on St Helena. I wonder where it is?? It's obviously got a good view of the horizon towards the east to get that sort of range. And the final interesting thing: FR24 shows no other aircraft anywhere within the 200 odd nm range of the receiver - just illustrates how remote St Helena is aviation-wise.