The problem is that, because MTS files don't have a common pattern for their end, R-Studio finds the end of such file just before the beginning of a new one. So, quite often a lot of garbage is included into found files. That garbage has to be removed manually in a Hex editor. You may use the R-Studio's for that.
Also, such files may overlap, that's quite often their total size may well exceed the size of the host disk.