Also bear in mind the more flexible options of casting streaming video playable in Android Chrome directly to Chromecast without download (open up video in Chrome, and go to full screen to get cast icon), or of archiving video on a PC/Mac on your local network and using something like Plex Media Server.
Do you mean restrictions on codec/container or content/copyright?
Former - not really, Plex can handle most containers/codecs and will transcode as necessary for the player device. Saying that you are better using the MP4 or MKV containers, H264 encoding, and AAC sound as these are directly Chromecast compatible so don't put any strain on the server as it doesn't need to transcode.
Content/copyright - see https://forums.androidcentral.com/e....tv%2Fabout%2Fprivacy-legal%2F&token=NESnGGQN. They don't check / police what content you host (and you are the host not Plex), but expect users to abide by the law in terms of content and rights and may act if infringements are brought to their attention. If your content is not entirely compliant in this respect I guess the risk of any consequences will depend on whether or not you share your library with other users and if so how widely you share it. Sharing is by invite only so you are very much in control.