I'd second @Bananaman on this one. the bus is still at a slight angle, and it looks as if the driver's move to the right began after passing through the 'choke' point at the W Maitland Street/Torphichen St guddle (AKA junction). To actually ride up on to the footway here (through pedestrians waiting to cross and street furniture at that time of day) would never seriously happen.
What the witness 100 metres away probably saw is the cyclist on the nearside of the bus as they were being overtaken/about to be overtaken, carrying on riding and perhaps unaware of the mayhem alongside, or thinking thank goodness the bus driver hit the tram and not me.
Overtaking a cyclist is the most likely scenario here, and perhaps there should be a clear indication "No Overtaking - all vehicles" for this section, and "No Left turn" (except cycles) for Manor Place, to avoid a repeat of the first coach-tram crash, caused I suspect because no one considered the 1.2m outswing which C&U sets as the maximum for large vehicles (ie HGV/PCV) - not a massive problem in a standard 3.5m vehicle lane but when you shoe-horn a lane in alongside the tram tracks and reduce the width to barely fit a 2.55m wide bus or truck....
Now if this, and the first crash had happened in England or Wales, the RAIB would have announced that an investigation had been commissioned, and an independent report was being prepared. However because this is now Scotland and NOT a heavy rail line, RAIB do not carry out crash investigations, and ORR does not regulate the tram operator - the matters are dealt with by Transport Scotland.
This could be very interesting as a pre-testing for independence, as clearly when (if) an independent state, then Scotland will need the equivalents of CAA, MCA, and ORR to regulate air sea and rail operations, and I would suggest an independent crash/incident investigation team/unit to objectively investigate all significant road, rail, air, and maritime incidents, and produce recommendations to prevent the same things happening a second time.
Just one of the things we'll need to sort out when/if we get a Yes result on 18th......