I use Registax for stacking video frames for planetary imaging, but the learning curve is steep and many online tutorials are out of date because the UI seems to change quite significantly between releases. I was pleased therefore when someone provided me with a link to Paul Maxson’s Registax 6 Tutorial in which he explains his methodology for processing images. Not all of it works perfectly for me, but it gets pretty close most of the time.
In case his page disappears at some point I’ll summarise here with my own experiences soon.