You can try
VLC from videolan.org. It is free, but you should donate if you use it (especially in a business environment). :)
It supports up to 32x playback speed - 32 seconds real footage in 1 second - so, 8 hours in 15 minutes.
But you should ask yourself - you really can catch up something in that speed?
And the more important thing is: your processor and HDD speed.
At 32x playback the processor should decode 32 times faster than at normal speed and your HDD should allows that big data rates, especially if the video is in HD.
Try it on your HW.
To clarify (re: comment) based on the real world (read my own) experiences.
At 1080p resolution, H264 encoded video is 2GB per hour (common movie sizes are 3GB per 1.5 hour of movie). On extremely well encoded videos you can get 1 GB/hour. So 8 hours video is approx. 8-16GB size, depending on the encoding quality.
HDD speed. On my crap notebook I'm getting approx. 13 Mbytes/s read speed. The HDD is old and, honestly it was not defragmented. That means that simple reading a 1.25 Gbyte file took 1 minute and 20 seconds. Reading (not copying) a 12 GB file took 16 minutes!
So, on my crap notebook I simply can't read an 12GB file sequentially in 15 minutes.
And about playback. On my notebook I can't get faster playback speed than 6.8x. ;( On my desktop (also not the best HW) my limit is 22-25x. Never got 32x.
Maybe, your experience is better, but remember: In theory there is no difference between theory and practice. :)
With good (current level) HW there should be "no problem" - therefore I said: try it on your HW. ;)