Hi,
I just created two actions for this.
WebDownloadRequest, which allows you to save any url content into any file. so it will work for your movies
and
GetPersistentDataFolder, which will let you find the folder you can download files on mobile.
with these two actions, you are good to go. I do use Avpro for all video needs, it's very expensive, but it runs litteraly everywhere without any issues, so as far as video playback, you;'ll need to see what you need, the ecosystem also have actions for the Unity video player, but I am not about it's performances.
Bye,
Jean