Back in the early 90's, there was no such thing as 1080p let alone 4K! But playing back small color video on a 25mhz Mac was possible thanks to QuickTime.  It supported only a handful of formats, but here I'll explain how to get any video from today playing back on a 1990's Mac.

First, I need some video conversion utility such as XMedia Recode.

Then, I configure a conversion queue in XMedia Recode with very specific codecs, because as I mentioned earlier, QuickTime for 68K doesn't support a lot of codecs and also, altough QuickTime 2.5 supports MPEG-1, which would be a no brainer to use, 68K CPU's back then were not fast enough to decode MPEG-1 in real time, so this is out of the question.  I'll be using Motion JPEG (12fps) as the video codec and PCM A-law (11Khz) as the audio codec.  Of course, I could crank up the quality here, but my 25mhz 68040 would begin to choke on more than this.  If I was dealing with a later 68K model or one with an accelerator card, I would be able to achieve better quality for sure.

Those are my conversion settings for this task in XMedia Recode:

The resulting QuickTime movie file (.mov) can be played back under System 7 with QuickTime 2.5:

See also: An interesting 1990's QuickTime supported codecs chart.