The "pausing" sounds similar to me. If I started a video, I would get the delay. Once it was playing, if I paused it briefly it would resume correctly. If I paused it for 10 seconds or so and then resumed it, the delay would be there again. I feel it's the Realtek, not the speakers. If you can find some headphones lying around plug them in and give them a try.
You can also try a USB sound adaptor. Go to Amazon and search for ...
SABRENT USB External Stereo Sound Adapter for Windows and Mac. Plug and Play No Drivers Needed. (AU-MMSA)
It's pretty much a sound card for about $9 and it has good reviews.