When using the rich content editor (RCE) for video recording, I have yet to find a specific time limit or file limit, but I have heard of recordings of more than an hour long not being an issue. That being said - the longer the video, the more likely it is to hit some sort of snag in either internet connection or server processing.
Generally (for loading and instructional purposes) you'll will want to keep the recording to under 7 min. Best practice for use of videos in instructional design is 3-5 min. Hopefully you find that information helpful for your use case.
One other item I would add, the course storage default is also 500mb, meaning recording a video through the RCE that reaches that file limit would not allow for any other items to be stored within your course. This 500mb course limit can easily be increased by talking with you Canvas admin.
My understanding was that adding media content using the Upload/Record Media tool in the RCE didn't count against the default course file size limit of 500MB. Media files are shown separately from Uploaded Files under the File Storage tab in Couse Statistics (see embed) but there's not a "remaining storage" number so I wasn't able to see the impact on the total. Perhaps it's related to account types?
That is my understanding as well. That is why we embed our audio and video rather than putting them in as files.