|Since you have an older computer there may not be much you can do.|
I have a computer I built in 2000 I still use that has good enough components it could display any online video nicely back then, but it certainly can't now, despite my 1500kbps connection speed.
How well video displays overall depends on
the capabilities of your system and it's graphics hardware - the faster your cpu and the more ram you have, to a point of dimishing returns, the better - the higher your mboard fsb speed the better (e.g. some P3s use only a 66mhz bus speed) - onboard graphics usually don't work as well as a card in a slot does - faster graphics cards work better than slower cards.
How well video works on the web depends on many additional things.
Once it has been downloaded to your computer, video often works much better because fewer limiting factors are involved.
E.g. How well video on the web works and looks also depends on:
- how good a connection to the internet and to where the video is you have, and what it's max data data transfer rate is - you can probably improve your average and overall max internet speed somewhat by using a TCP settings tweaking utility e.g. such as the ready made optimized settings in TCPOptimizer, if you haven't already used one (default Windows TCP settings don't allow your internet speed to reach it's full potential). If you have a "lite" or slower internet connection, you're not going to get as good video as you would for a higher max speed one.
- what the streaming (data transfer rate) requirements over the internet are for that video - you can often alter default settings of whatever program is displaying the video, or choose a slower streaming rate, and get better video with fewer dropped frames (pauses, freezes, black frames, "jumps" because of missing frames) - older videos or those that require a lesser streaming rate often work better on older computers. Lower resolutions, 16 bit rather than 32 bit color, a windowed video rather than full screen, will work better.
Black and white videos often work much better than color ones.
- if your high speed internet is via a cable connection how many users are online close to you at the time - the video will work better when fewer users are using the cable internet locally.