I am having a very confusing and frustrating issue with getting videos to play back on Youtube without camera movement being choppy. Apparently I can't post a link as I'm a new user, but if you got to 'Dreamtime Visions Productions' on Youtube and see my videos all of them have the same issue. The videos play smoothly on Premiere CS5, smoothly with only the occasional stutter on long track shots on WMV and VLC when compressed and streamed on Vimeo. However, on Youtube using Firefox camera movement is very choppy on my computer. When I stream the videos through VLC or download the video and play it on VLC, it is not choppy. I have asked various people to watch the video both in Australia and overseas, with some finding it choppy like me and others saying it is smooth. What could possibly be causing this? Is it something Im doing wrong in my settings, if so what? Is this an issue with Adobe flash interacting with computers/Internet/video card? If so, can I change something in my settings to stop the issue? Ive tried so many tests, with no success. Video and test details below: Original footage: Recorded from a video game with graphics settings on high as individual jpeg images at 120 fps, 1280x720, sound clips mostly 44100 with some higher/lower. Original footage converted into uncompressed video with Lagarith codec on Virtualdub. Premiere sequence settings: 59.94 fps, 1280x720, square pixels, progressive, 48000hz, stereo I then have two copies that I encode using x264/AAC. One is a downloadable version at 59.94 fps, the other is downscaled to 29.97 fps for Youtube/Vimeo. GENERAL X264 RENDERING SETTINGS: Avisynth: AVISource("J:\Final Youtube Tests\Test 7\Test 7.avi", audio=false).AssumeFPS (30000,1001) #deinterlace #crop #resize #denoise ConvertToYV12(matrix="rec601") X264 settings: I have screen grabs of the exact X264 setting I've been using, but can't post them yet as I'm a new user. Here is a summary of the main settings from megui: program --level 4.1 --preset veryslow --pass 3 --bitrate 8000 --stats ".stats" --deblock -1:0 --keyint 15 --min-keyint 8 --bframes 2 --ref 5 --merange 32 --partitions p8x8,b8x8,i8x8i4x4 --psy-rd 1.0:0.15 --no-fast-pskip --output "output" "input" TESTS: Rendered in the following formats, but all have provided same choppy Youtube playback: x264/AAC mp4 through Premiere CS5 WMV through Premiere CS5 Uncompressed render from Premiere CS5 and x264/AAC through Avisynth/Megui Experimented with many different settings, but all have provided same choppy Youtube playback: Rendering new footage out at 30 fps instead of 120/sequence settings/export all at 30 fps Putting a 59.94 fps version on Youtube instead of downscaling to 29.97 fps x264 levels (3.2 and 4.1) 300 max keyframe interval, 30 minimum keyframe interval GOP settings 0 vbv buffsize and 0 vbv maxrate 78125 vbv bufsize and 62500 vbv maxrate Very frustrated and no clue how to fix this issue. I can provide more details if needed.