Windows – Why won’t video play smoothly when saved on laptop Internal hard drive, but

In my experience, something has changed that is causing the machine to become just a bot more resource limited and you are only noticing this when you view video, which is pretty resource intensive. Just because you haven't installed 1 major resource hog, doesn't mean the same affect can't be achieved by installing lots of little resource hogs. Areas I typically target first:

1. Add / Remove programs. Remove old just you're not using. It's amazing how it adds up.
2. Look at the continuously running applications in your task bar. Java console, print monitors, every developer on the planet thinks their cheesy program is the most important thing you'll ever run & feels like it belongs permanently running with a little blinking status icon on the taskbar. Printer software is the worst. Don't ever intall printer software unless you can't print without it.
3. Startup programs. Seek & destroy anything you don't need.
4. More ideas here and here.

Hm, very perplexing situation; with those specs one would definitely expect better performance. Have you tried playing those same media files on another computer? It's possible that the files themselves are corrupted, which could be causing the skipping.

I would also suggest trying some other players to see if they work any better. According to Wikipedia, some M2TS files can be played by a variety of media player programs, listed in said article. The ones I would recommend trying are Windows Media Player, which has very good codec support in Windows 7, and VLC, which can play just about anything.