Video Streaming adds multiple possibilities to the functionality of a web portal. Instructional, demonstration (sales or functional), educational or technical guidance videos are all possibilities either streamed from the clients hosting provider or linked from the popular video hosting sites today (youtube etc.) The choice of which platform to stream from depends on a number of factors including privacy, web hosting policy, security and budget just to name a few.
Platforms or media delivery options are pretty much unlimited now - filters, codecs and converters have made multiple formats streamable, and the only issues to consider really are bandwidth and quality. Here's an example of a flash video coverted from windows media (WMV) hi def;
This video was imported from an old Sony hi8 machine, edited, saved to avi and then ported to flash video format for bandwidth economy.
As with all visual (and audio) format presentations, the biggest consideration at the outset is to capture the subject in as accurate (hi resolution - digital) a format as possible in order to have as many options as possible through the processing steps, and out to a high quality final product.