Roku Direct Publisher

[Baradanikto]

I've discovered some videos on my channel that seem to consistently buffer.  I haven't been able to narrow down any reason why it happens.  I'm running on a new Ultra box (connected via wifi) with the video content streamed from Amazon's CloudFront service.  The buffering does not happen on all videos, so, I'm not sure if this is a problem with the Roku box, or, the Amazon service.  My current download speed is 60+mb.

Of note also, when watching other services, like Hulu, I don't see the same buffering.  Does anyone know how to troubleshoot this type of problem?

UPDATE:  The buffering seems to happen on newly uploaded videos.  I don't know if this is a caching issue.  I've looked on the Developer Portal at some of the statistics, but, they're not too helpful.
UPDATE:   I captured some log files from AWS.  If any one can help with the analysis, I'd appreciate it.

[PeaceFestival]

I am seeing the same issue, only certain videos do it, and it's not the format, length or encoding--I changed all variable with no luck. I'm also on an s3 bucket, but all the other videos play perfectly. 
Does anyone know if there is a known bug, maybe in how a video is rendered, that could be the culprit? I'm using MP4.