So by default the framerate is so jagged that the game is unplayable. It's a struggle just to try to use the cursor on the options menu.

One solution I've found is to used Reduced Color Mode and set it to 16 bit, but that causes the movies to be black screen or not load properly, like it will literally just continue showing a loading screen or an image of your desktop while movies are playing.

Is there any way to view the movies, without the unplayably jagged framerate?

In Win7 or Win8? Do you use any compatibility mode?

Same problem. Win 8.1

Ditto with 8.1.

And the odd thing is, back when I had Windows Vista, all I had to do was install an older version of QuickTime, and that fixed everything. Sadly that doesn't work anymore.

IIRC, there is no definite solution for Win8. However, the problem is solved easily in Win7 and other earlier versions of Windows. If I'm not mistaken, some users even had to install Ubuntu on VM and to run the game in WINE to be able to play it in Win8.

Yeah, just brought the game... Tried all the solutions on the forum, either my mouse is lagged or the movies dont load.

The movies can be watched separately, therefore it is no big deal if you can play without them.

Win 8.1 here, too. I had no issues playing this on Win7 last year. Now everything's so laggy I can't even tell where I'm clicking...

http://www.gog.com/forum/septerra_core_legacy_of_the_creator/graphic_fix_for_windows_78

Check this thread.