Why does my video glitch after import into Premiere?

For some unknown reason when I import video into premiere the video glitches horribly when played on my timeline. The source footage when played outside of premiere [in a program such as QUICKTIME], plays completely normal. After reading many threads regarding this topic I have done much trouble shooting [deleted media cache, changed audio hardware, decreased playback quality, imported into new project, upgraded premiere pro, ect.] but still without any luck. I am working on a mac, and also updated it thinking it may be caused by the computer and not premeire. I am still using the same equipment [luminex G7, same SD CARD], as well as the same settings within premiere that  I have on previous projects, which is why I don't understand why I am having this sudden unresolved issue. One thing that I have also noticed is that prior footage that I had previously used from different projects now glitches within premiere as well, when before that footage played fine and my workflow was uninterrupted. Any help regarding this matter would be greatly appreciated. As you may be able to tell from my description of this problem, I am not an expert by any stretch of the imagination.  I have always enjoyed working within premiere and been able to find my way out of probelms I have faced with the software, until now.  Included in this post is a short clip of my experience. Thanks in advace for any and all help!