I finally can normally watch videos on docker, but why should I add these thing?

docker run -it -h myubuntu \
--net=host \
-e DISPLAY=unix$DISPLAY \   #What does it mean?
--device /dev/dri:/dev/dri \ 
#graphic driver device? I need it to enable vaapi hardware decoding.
--device /dev/snd \   #I saw people said that I need it to have sound output.
-e PULSE_SERVER=unix:${XDG_RUNTIME_DIR}/pulse/native \ #what does it do for?
-v ${XDG_RUNTIME_DIR}/pulse/native:${XDG_RUNTIME_DIR}/pulse/native \          #why do we need this?
-v ~/.config/pulse/cookie:/root/.config/pulse/cookie \  #Why do we need this?
-v /tmp/.X11-unix:/tmp/.X11-unix \  #Why do we need this?
-v ~/下載:/LAI  --privileged --name myubuntu ubuntu