MP4 Bitrate Issue

We are abandoning our LMS and I need to convert all of our SCORM courses to MP4.  They will be hosted on Brightcove but I'm having issues with the conversion. All of the files I upload to Brightcove are blurry. I've been told that the MP4s must be at least 4000mbps. I've played around with the bitrate settings in Captivate, but that's only made things worse.  Has anyone else had this issue?