Output video file size too large compared to input

I’m very new to Blender and video editing in general. I am attempting to do a simple modification to a video file. Currently I have a 78 MB mp4 video file that is just over an hour long. I want to take a static image and cover up part of the video for the first 20ish minutes, maybe a 40th of the screen. I have managed to get all that to work and the end result looks exactly like I want it to. The problem is I can’t get close to the original file size without losing a large amount of detail. Whenever I adjust enough settings to get it down to about 80mb the video is very blurry and useless. But so far the only output I’ve gotten with decent video and audio is 562 mb. I’m sure I’m just doing something simple wrong with the format and codec of the video and audio, seeing as I’m very new to this (I’m using Blender because it seems to be the best free program that can do what I need), but I can’t figure out what. I don’t have to get the exact same size, but needs to be close.

Good assumption but apart from not using paragraphs in your post, you’re not doing anything wrong. Blender uses ffmpeg for encoding but its encoding flags are crap and you can’t really change them much. You’ll get the file size down for a good quality by encoding with something else than Blender.

ffmpeg/avconv can do it when you specify the encoding flags. Could re-encode the output, or if you have space, output an image sequence and encode that.

Ok I downloaded ffmpeg directly and am messing with it. I’ll probably figure the best settings out eventually, but any suggestions for encoding flags or places for good tutorials?

HandBrake can help u with this too. Check https://www.youtube.com/watch?v=rHJ2W0Ofb44 for a tutorial.