Most news anchors don't just wing it though, except in the rare case of live breaking news. The vast majority of the time they read a prepared script off a teleprompter, which is written by - you guessed it - writers. Sometimes the anchors are also the writers, and sometimes they don't always stick 100% to the script, but whoever wrote it and whether it was followed aside, there is a script. I don't see why news channels couldn't publish it alongside the video - it would be useful for hearing-impaired audience at least.