The best ones are likely about to get here a little later this year, namely:
Instagram Reels, which is already being tested in Brazil.
For now though, you have byte, which is made by the same people who made Vine that heavily inspired Musical.ly/Tiktok. This is already out, but it's much more limited than TikTok. It's slowly adding ...
I recommend you to try Fastreel. For creating a video you need - add your files, select the transition style and set the image display duration, if it's necessary add audio track (or choose one from the library) and save the result.
There are three major video players on Linux:
VLC, which you've indicated you don't want,
MPlayer and forks (MPlayer2, MPV)
Xine and assorted frontends (GXine, etc.)
All three of them meet the "plays many formats" criteria. All three will stall, jump, or otherwise act poorly if the CPU is overloaded or for some types of video corruption. This ...
I very much like to use the windows version of the MkvToolNix Tools you can find at https://mkvtoolnix.download/downloads.html (There are options for a wide variety of OS).
You can add multiple video files as input, and then choose which video track and which audio tracks you want to merge into a new mkv file. You will just have to make sure you identify the ...