Enable hardware acceleration for video playback

You can try enabling hardware acceleration to fix lagging video playback.

1. Open a terminal or connect to your Raspberry Pi remotely.

2. Then just update /etc/chromium-browser/customizations/00-rpi-vars file with the following content:

   CHROMIUM_FLAGS="${CHROMIUM_FLAGS} --force-renderer-accessibility --disable-quic --enable-tcp-fast-open --enable-gpu-rasterization --enable-accelerated-video-decode --enable-native-gpu-memory-buffers --ignore-gpu-blocklist"

3. Reboot the Raspberry Pi

Related links: Chromium configuration