I did, and the codec seemed to help at first. I didn't have new incident with display problem for a couple of days and then it returned.
The settings of the codec looked very complex and we just used the default settings. Not sure if changing any of the settings would help eliminate the problem... but overall, the video display issue occurred at a low rate: about 10% of the subjects were affected and with each person, the issue happened to no more than one video clip during the entire experiment, which contained 16 video clips plus 1 practice clip. So I didn't lose too many data due to this technical issue.
Thank you for the follow-up. A new experiment will start soon. I will let you know if I have more to report.