*PLEASE NOTE* All my videos are for feedback purposes only in an attempt to reach the driver, after all if they didn't know they did right/wrong, how will they learn?
1. give priority to traffic approaching from your right, unless directed otherwise by signs, road markings or traffic lights
2. check whether road markings allow you to enter the roundabout without giving way. If so, proceed, but still look to the right before joining
3. watch out for all other road users already on the roundabout; be aware they may not be signalling correctly or at all
4. look forward before moving off to make sure traffic in front has moved off.
So regarding the driver in question (not the dash cam) i would assume they didnt follow point 1 as there was a vehicle approaching from the right.
Im not sure where it says give way to vehicles already on the roadabout (it just says look out for them), and if the other driver had followed point 1, there wouldnt be a issue
I think the poster needs to take a closer look at this video. The silver car is clearly over the give way lines before the camera car arrives at the junction by a good margin; also, the high hedge on the camera cars left would have hidden the camera car from the silver cars view until the last moment. The camera car should have approached the junction with caution and given way to the silver car. I also think it's a poorly laid out juntion with the give way lines too far from the junction on the road merging from the left.