I have a user that is trying to play purchased stock HD .mov movie files. The movie is only 8meg in size and is playing jittery on his windows 8.1 machine. The machine seems to play all other HD movie files with no problems and it is a high spec machine that should play this video with no problem. For some reason it is struggling with recent .mov files. 

I have updated to the latest K lite codec pack and also tried it in the quicktime application.

I am happy to upload the file for someone to also look at it on their system.

Media File Information

General
Complete name               : C:\Blue Star Space SHORT ALPHA-H264 MOV.mov
Format                      : MPEG-4
Format profile              : QuickTime
Codec ID                    : qt  
File size                   : 8.69 MiB
Duration                    : 14s 0ms
Overall bit rate            : 5 206 Kbps
Encoded date                : UTC 2008-05-31 14:53:18
Tagged date                 : UTC 2008-05-31 14:55:49
Writing library             : Apple QuickTime

Video
ID                          : 1
Format                      : AVC
Format/Info                 : Advanced Video Codec
Format profile              : Main@L4.0
Format settings, CABAC      : No
Format settings, ReFrames   : 2 frames
Format settings, GOP        : M=2, N=25
Codec ID                    : avc1
Codec ID/Info               : Advanced Video Coding
Duration                    : 14s 0ms
Bit rate                    : 5 203 Kbps
Width                       : 1 440 pixels
Height                      : 1 080 pixels
Display aspect ratio        : 16:9
Original display aspect rat : 4:3
Frame rate mode             : Constant
Frame rate                  : 25.000 fps
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 8 bits
Scan type                   : Progressive
Bits/(Pixel*Frame)          : 0.134
Stream size                 : 8.68 MiB (100%)
Language                    : English
Encoded date                : UTC 2008-05-31 14:55:48
Tagged date                 : UTC 2008-05-31 14:55:49
Color primaries             : BT.709
Transfer characteristics    : BT.709
Matrix coefficients         : BT.709
Color range                 : Limited

Other
ID                          : 2
Type                        : Time code
Format                      : QuickTime TC
Duration                    : 14s 0ms
Time code of first frame    : 00:00:00:00
Time code, striped          : Yes
Language                    : English
Encoded date                : UTC 2008-05-31 14:55:49
Tagged date                 : UTC 2008-05-31 14:55:49

• Edited by Deleting objects from lost and found problems 10 hours 59 minutes ago

I shall suggest you to uninstall and reinstall updated QuickTime.

I have just tried that and now tried it on several different windows 8 and 7 machines and it seems to be consistent through them all.