The switching centre at TVC have experienced a few problems with the feed to them from News24. When the clock disappeared they were transmitting the reserve (back-up) feed while they fixed the main one.
Generally when they switch, you might notice some green flashing on screen - this is an artifact of Digital Transmission
I remember in the early days of Corporate Weekend 24 on two the BBC had a few problems there. It seemed now and then at that the top of the hour that when BBC Two joined News 24 the program for the first 10 minuites or so was broadcast in 4:3. Then it switched back to widecreen. Very dodgy that was. It was the only time I remember seeing News 24 in 4:3!!!!!!
Im suprised BBC News crop 80% odd of their footage. They are the only news organisation in the world to have 16:9 news and even then only the studio footage and 20% max of the news is 16:9- and thats on a good day with lots of london footage. Over the alst week with moree footage ont he US tragedy its been more like 5% 16:9. Hmmm a bit like CBBC on choice then?