Install this for displaying embedded cover are picture in your video in Dolphin.

README

If you are using paru, just do `paru -Ui`

Then open Dolphin, go to Configure Dolphin > Preview, and tick `Video filed (kffmpegthumbnailer)

PKGBUILD

_pkgname=kffmpegthumbnailer
pkgname=$_pkgname-svn
pkgver=r493
pkgrel=1
pkgdesc='a video thumbnailer for kde based on ffmpegthumbnailer'
arch=('x86_64')
url='https://github.com/dirkvdb/ffmpegthumbnailer/tree/master/kffmpegthumbnailer'
depends=('ffmpeg' 'ffmpegthumbnailer' 'extra-cmake-modules')
makedepends=('subversion' 'cmake')
license=('MIT')
source=("svn+https://github.com/dirkvdb/ffmpegthumbnailer/trunk/kffmpegthumbnailer")
sha256sums=('SKIP')

pkgver() {
  cd "$_pkgname"
  local ver="$(svnversion)"
  printf "r%s" "${ver//[[:alpha:]]}"
}

build() {
  cd "$_pkgname"
  cmake . -DCMAKE_INSTALL_PREFIX=/usr
  make
}

package() {
  cd "$_pkgname"
  make DESTDIR="${pkgdir}/" install
}