You can record and watch.
A video can be recorded in 1080p but you can still watch in 720p if you want.
Either way 720p should be fine to read plates/signs. If you can it's probably more to do with poor quality video or vibration.
For 10 quid i doubt it will be fantastic and the Amazon reviews pretty much show this.
Ok for a bit of fun, but I wouldn't want to rely on the video for insurance purposes.