tool of my choice: avidemux (freeware)
target fps to 150 and frame blender to 3 (this merges 3 frames into one). Additionally, reduce the format, to keep the video under the permitted 97.7mb, and resample to eliminate any timecode errors, which occasionally cause trouble after saving the original
With fps and frameblender I play as needed. 150n3 (as I call it) is my standard, but sometimes it also becomes 100n5, or 150n2
it always depends on what I want to show… My highest compression so far in a timelapse was 900n100, in the starlighthouse-topic. I packed the time from sunrise to sunset into 35 seconds: