5.2.3 is a mainly a bug fix release and you can read the details in the first part of this topic:
Krita Monthly Update – Edition 17
Note the reworked default ffmpeg profiles for the built-in ffmpeg.
I’d suggest that you download and install it.
re. video sizes: My monitor is 1600 x 1200 so there isn’t any point in me watching a video that is larger than that. If I produced a smaller video, it would be scaled up by the video player and a larger one would be scaled down.
As a rough guide, the usual YouTube video size is 1920 x 1080.
If the Export Timelapse FPS options are both 1, then the recorded canvas images will be presented at a rate of 1 per second in the video.
That has nothing to do with the rate at which they were initially captured.
The Export Timelapse process does not know what the original capture rate was. It just sees a collection of image files with numerical sequence names then it stitches them together into a video file.
If you want the video to be twice as fast then set both Input and Video FPS to be 2. Setting them to 5 would make the video 5 times as fast.
Setting Input and Video FPS to be different values has caused problems in the past and I don’t know if that has been fixed so I’d suggest that you keep them the same unless you want to experiment.