What a psycho.
Many years ago when I was a racing club rider we used to introduce our young/new riders by way of Sunday club runs. Sometimes there could be as many as 20 or so of us on these outings riding 2 abreast as we are allowed but going single file when needed to let vehicles pass. On one such occasion we had a very aggressive van filled with builders wanting to fight us because we delayed them for a few seconds. They would not have stood a chance of course because of our numbers and we were very fit plus we had 2 additional club members with us, one a policeman the other a police woman. We avoided the conflict due to having some very young riders with us who were visibly afraid.
On reflection I now wish we gave the builders what they wanted/deserved, a thoroughly good hiding.
I'd say all the crap about council functions e.t.c sounds like a daily mail reader but I think any type of reading may be beyond the driver of the camera car if he can't appreciate he was at least as bad as the Nissan driver in this video
So he was in front of you when two lanes merged and you accelerated with the specific intention of cutting him off probably because you knew you had a dashcam and wanted footage ( assuming it's your footage and you havn't stolen it to get youtube views .
You as much of a problem as the guy in the Nissan with your aggresive driving mentality at some percieved slight of another care daring to move one space ahead of you .
There is no rule that the car in the outside lane gets priority ,you are mistaken although it does explain why you were in that lane coming up to the roundabout when the lane to your left was clear .
2 sides to every story, Perhaps she was warning you off for driving too close?
If you leave a safe gap you would be able to stop safely even if she stamps on her brakes.
https://www.gov.uk/government/publications/the-emergency-workers-obstruction-act-2006