That's interesting. I downloaded all the .MTS samples that were available here. [https://standaloneinstaller.com/blog/big-list-of-sample-videos-for-testers-124.html]
I added a couple of .MTS files I made by converting MP4 clips on an on-line converter, here. [ https://convertio.co/mp4-mts/ ]
All the files were seen by Videowave's file selector, although the two that had been converted had 'prohibited' signs on their thumbnails.
Each of the files loaded and ran in Videowave - even the converted files. There were some strange effects - the lion-sample one has weird speed, and P6090053 was pitch black, but I think that's down to the individual clips rather than an inherent defect in Videowave.
In any event, I'm getting different results from myguggi, and it doesn't seem that Videowave is unconditionally broken.
Lamberto, can you attach a couple of small MTS files from your camera so I can try them, please?