I think that’s most likely the problem. You’re running a Plasma desktop on a machine with only 3.5 GiB of usable RAM — I do not know whether you have a swap partition, because you haven’t told us.
I have 3.5 gigs of RAM too but I can run Plasma along with many applications very smoothly. The ootb memory usage is about ~900MB on Manjaro KDE and that’s enough for many GUI applications. So I don’t think RAM is the problem here.
That to me still looks like the limited amount of RAM appears to be the problem, and I strongly suspect there’s no swap partition on that machine.
I have just watched a video in VLC on my fully updated Plasma system over here — Manjaro Stable branch — and I haven’t had any problems. Not even any stuttering of either the video or the sound, while the system is also busy at defragmenting a roughly 730 GiB btrfs partition on a spinning rust drive in the background. But I do have 16 GiB of RAM in my machine.
…looks like you try to use vaapi but have it not correctly configured. Should more look like this:
[~~~~~~~~~~~~ ~]$ vlc /home/~~~~~/Videos/test.mkv
VLC media player 3.0.17.4 Vetinari (revision 3.0.13-8-g41878ff4f2)
[00005575c3f05630] main libvlc: VLC wird mit dem Standard-Interface ausgeführt. Benutzen Sie 'cvlc', um VLC ohne Interface zu verwenden.
[00007f3b94007d60] gl gl: Initialized libplacebo v4.208.0 (API v208)
[00007f3bc0c20990] avcodec decoder: Using Intel i965 driver for Intel(R) Ivybridge Mobile - 2.4.1 for hardware decoding
[~~~~~~~~~~~ ~]$
Turns out the problem was with the driver I was using. Because it’s my first time using a system with two GPUs. I (perhaps by accident) installed both open source and proprietary display controller drivers. And somehow it caused issues in VLC.