I have no issues.
It would help to know what device you're trying to watch the videos on as well as your browser and operating system. You may also want to try watching their videos directly from YouTube instead of from the PAPA website to see if that fixes the problem.
That said, now that all their gameplay videos are primarily on YouTube, it's important to know that YouTube doesn't default to HD streams unless you're logged in to your Google account and have set your profile up to enable HD by default, otherwise every time you go to watch a video you'll need to adjust the stream quality to the desired level using the gear icon.