0:04 Poor over-take. Far too close, on the apex of a bend, with oncoming traffic.
0:12 Poor over-take. Too close, approaching a roundabout.
0:15 Poor cycling. You're approaching a roundabout, riding in blind spots. The car in front should be checking their mirrors for other road users filtering either side; however this is no guarantee they will have seen you. Further, the car in front could have gone in any direction. Far better to simply take primary and stay behind the car in front at a suitable distance - it makes you far more visible and may help deter dangerous over-taking.
0:28 Perfectly fine. Over-took the other cyclist riding secondary, giving plenty of room.
0:31 Reckless and dangerous over-take between pinch points.
To the person on the bike. Try to stay in primary where appropriate. Between these roundabouts would have fit such criteria. Get a horn. You cannot change the way some people act on the road, but you can control the way you react to it. You have to try to stay in control and make people aware of your presence at all times.
Where possible, report what you consider dangerous or reckless driving them to the local police - some forces are taking the appropriate action against a minority of drivers like the one's shown in the form of an online reporting system where you can submit footage. Hopefully more will get the message and they will think twice - people can and do die because of drivers like this, who should consider a fine far more preferable to taking someone's life because they're too pig-headed to share the road AS REQUIRED.
It's very easy to lose your cool - and lose your control. Don't come down to the level of an idiot. Your life is far too important.