RE: Why do they have to make their own software?
"There are plenty of free video players around. The porn shops don't insist I wait for them to develop their own players. Even Google/youtube do not insist that I use flash.
Get a clue BBC/CH4/...: stick to making and broadcasting content and leave the custom software disasters to the NHS"
The problem for all of the channels is simply copyright. Most Channels (especially Channel 4 which actually has no production facilities) rely on other companies to produce their programmes. These companies often insist that their output is protected against illegal copying/downloading. The best way for the channel to do this is use some form of DRM. You may argue about whether DRM is right or not all you want, but the fact remains that the programme producers are actually within their rights to insist on it, and they will.
How many opensource or free codecs or video player support a full DRM system that is easily distributed to thousands of users? WMP has it's faults, but DRM is piss easy on it. (as long as you are running Windows).
Google/Youtube does not have that problem. Where they did have content from certain producers (on Google Video), they did use a system with DRM, but 98% of their content is not licenced..