my videos look clearer ?..will they load faster when i skim through?
Videos will not look 'clearer' as a result of a faster video card. They might 'load faster when you skim through', I don't really see what you mean.
The main benefit from a faster video card is able to play games at higher resolutions and at higher detail settings. The ability to play HD (High-Definition) video more effectively is a plus.
However I would highly recommend against upgrading that computer, any money you spend will be wasted on it (you won't be able to increase the performance by very much) - you would be much better off saving to buy or build a new machine with a multi-core processor.