The first thing that come in to my mind is that you maybe have made your videos in a high or memory taking file format.
When you do your videos you can do them in any format you like but when you convert them at last it should be in an format that of course is as high resolution that you need but same time in a video format that only fill so low in mb as possibly.
You should experiment to make the file´s in format thats low in mb but still in good quality.
Its like making websites, one need to have pictures and movies that look great but it has to be converted to format an resolutions that is so low in mb as possible or it takes forever to load.
When you use Widgetcast you need to think off how many mb all the stuff you put in has so you can go so low in output mb as possible.
I dont know if this help you but try experimenting, and good luck. :)
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