Unless it is completely broken, it shouldn't be taking battery power when not in use. Keep in mind though any time it is sending video to a tv, it is "in use". Its not like netflix and youtube where it just sends a link and you can go away.

There is no way for videostream to work with non chromecast streamers "up front" because they use their own front ends. However there are android apps for the android streamers to make it look like a chromecast.

afaik videostream is chromecast only. Using an app that makes android devices look like a chromecast are still bound by chromecast profiles, thus no hevc support.

Is this when you are playing a movie? Videostream will transcode videos that won't natively play on chromecast, this is very cpu intensive.

No related to the size, but rather a bad encode. Usually seeking issues are related to the player requiring a keyframe to go to. If your video was made with very few keyframes then moving from one to the next may span many minutes. Try another copy of the movie? If it is something you ripped, use another program to rip it.

Does it NOT work? Is it videostream that requires internet? Cause chromecast shouldn't.

No, there is no way to synch the 2 streams between the pc and the chromecast. Remember the player is the chromecast, not your browser app. You would better off be asking how can I make my chromecast output audio to my pc speakers.

Why are you compressing your movies in rar? The movies are already compressed. RARing them is redundant.

chromecast uses a large buffer, there is no means of synching the audio with the video on the chromecast.

The video file is bad and should be re encoded.