Blackstone Chronicles (full name John Saul's Blackstone Chronicles: An Adventure in Terror) is Windows 95/98 game by Legend Entertainment that has the same problem with choppy QuickTime videos on newer Windows as their other game Wheel of Time. There is a patch for Wheel of Time that solves the video problem also in Blackstone Chronicles. I tested it only on Windows 10 but it might work on other Windows systems too.

You can download Wheel of Time patch here: MediaFire or here: TinyUpload

How to use it: Install the game (no need to install Quicktime that the game installer offers), extract the patch zip archive and copy all files to the game directory.
How it works: The game videos use old Quicktime installer that cannot run on modern systems and with more recent installers are videos choppy. The patch replaces Quicktime with Wine for Windows so Quicktime install is no longer needed.

When this patch is applied, speech in the game does not work when clicking on objects with error "missing ADPCM sound decompressor".
How to solve it: All ADPCM WAV files from sounds and voice directories of the game should be converted to PCM WAV files. There are various converters available on the net, I used Switch Audio File Converter which is free for non-commercial use.
I used version 6.27 (actual free version has limit for number of converted files) that can be downloaded here:
https://switch-audio-file-converter.en.uptodo … indows/versions
or here:
https://www.mediafire.com/file/1o7qcr8y54otfv … e-6-27.zip/file

How to use it: Add wav files to Switch (drag and drop them to window or choose add files), choose below as output format .wav (in the options should be PCM uncompressed) and convert them. You can convert many files at once and let the program automatically replace original ones.

The game offers playing with low-res or high-res videos. Only high-res videos that are available on the second CD of the game should be used, low-res videos from the first CD sometimes flicker with green color.