from a Canon HF S100 using HandBrake from www.handbrake.fr and did not notice any "motion blur". If there is fast action in the video capture, it may be due to a 1/60 second shutter speed (that's a long time when things are moving fast). Generally, interlacing artifacts are every-other-line sync issues, not "blur". As well, AVCHD-compressed video and fast motion don't get along well at all because of the way AVCHD compression works... But we can't see what you see.
I'm looking to import a .MTS file into imovie to edit the clip and upload it but I have to convert it to a MP4 to do so. However, to watch the .MTS file without getting a motion blur, I have to turn the deinterlace mode "On"...But when I convert the file to an MP4 it doesn't convert with the deinterlace mode on. Is there any way to convert the file with deinterlace mode on, or is there another relatively cheap/free software like iMovie where I could import/edit videos and upload them without doing the conversion.

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