SUMMARY STEPS TO REPRODUCE 1. in dolphin select a video (mp4, ts) 2. go to the data panel 3. click on the arrow button OBSERVED RESULT a dolphin freeze EXPECTED RESULT dolphin plays the video SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: 5.22.5 KDE Frameworks Version: 5.86.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION kde gear 21.08.1 no problem with .mov video
I solved the problem for mp4 video by instaling gstreamer-plugins-libav. For ts video, I still get a freeze.