Do you use Skype all the time? Is Skype maxing out your Ram? Worth a check.
If you've not used Malwarebytes Anti-malware, I'd throw that on there, and get it scanning ASAP. It's not a true antivirus product, as it checks for other things as well. It checks for any sort of "ad-ware" or "malware", and it's the best scanner out there in general. If it finds anything, remove what it finds, reboot, and scan again.
Also, you could try cleaning up things - look at CCleaner and Glary Utilities (both my personal recommendations anyway) - scan and clean with them, see what you end up with.
And make sure you don't have any app that is loading up huge log files - check your C drive to be sure not too full. I realize it isn't all that often this happens anymore, but it can make a difference.
RAM - how much physical memory do you have? Is it less than 4GB? If so, that could be a problem.
Latest Flash player? Latest version of Java? Check both out at their respective sites. Another option is to just go to
and use their installer to install up to date versions of any run-time items you use (java, .net, flash).
What website has the video? Is it ANY video on ANY site, or is it just on a certain site? Some sites use other players, like the Real Player or Quicktime. So that could be an issue as well. If so, you'd have to install their players or else find a 3rd party app/plugin that will handle that type of audio/video file for you without the normal application.
Processing speed - if you're running say a Celeron processor or an older processor (pretty much anything older than Core 2 Duo will run pretty slow now... and anything less than Core i... may run slow on some items.
Speed of your hard drive can make a difference as well if you are noticing slowness overall. It's not always the case, but if you have a particularly slow drive, that can make a difference. If you don't need any real storage space, and have money to spare and want to spend it, an SSD would be a worth while upgrade... especially if you're comfortable installing everything from scratch. Just make sure you have a Windows install disk, or else possibly that you can mirror your current restore partition (assuming there is one) to the new SSD before attemping to install that way.
Anyway, that's probably too many different options. Start with Malwarebytes, and go from there. By the way, I've seen and heard back from others who have used any one of the above fixes at different times, different scenarios where that one item made a mammoth difference. So just spends upon your details as to whether you need 1,some, or all changes. Obviously the CPU is not likely going to be something you want to even consider changing on a small laptop (well, most people wouldn't), but that's always something else to consider. I don't think I'd bother with that part, though, personally - just doesn't seem worth the hassle.
"But thanks be to God, which giveth us the victory through our Lord Jesus Christ." 1 Corinthians 15:57