If I am playing back a recorded show, is it possible to scan forward? I know you can fast forward, where you don’t get to see the recording moving forward, but most tv remotes have a scan forward, where you see the recording in fast movement and get to stop where you want.
It depends on the source. At best you get thumbnails every 10 seconds or so, but it depends on what channel/app you're using.
Roku has no provisions for recording anything. Any recording/playback abilities are provided by whichever service you are streaming through the Roku, on that service's own servers. The playback controls are whatever that service has programmed into their app.