iPlayer
 

Having given up TV (not that the licencing gestapo believe me) I have used iPlayer a couple of times.

On both occasions I gave up before long because of the jerkiness/freezing. Is it usually like that, or do I need to have words with my ISP? YouTube videos play normally if that's any indication.

Youtube videos are often available in a range of bitrates/resolutions and tend to default to a lower setting.

iPlayer can be a PITA at times, depending on demand / line speed. Streaming over wireless networking slows it as well.
My experience is that the ITV service is even slower -though that could just be a local peculiarity.
But in essence, all you can do is optimise your internal network, check the connection speed from the ISP, and make sure the software on the machine is optimised. Make sure you have the later version of Flash, if you are downloadin for storage make sure you have the latest Adobe Air version, get rid of old temporary internet files - and try other browsers. I hate to say it, but I find Google Chrome tends to give slightly better results - but that could just be a peculiarity of my computer. You may also find that having RealPlayer installed on the PC may slow things down as well: the Youtube download feature can hinder flash streaming, its not compatible with FlashPlayer
What else? Make sure the hard drive isn't full, fit extra RAM, and make sure the virtual memory settings are set to "automatic"
Finally, during playback right click the video and set the flashplayer settings to allow "unlimited storage"

Thanks for those suggestions.

I'll give them a try tomorrow when I'm a bit more awake.

Have you tried their diagnostics test here ? What sort of performance are you seeing ? Was it ever good ?

If you are having trouble watching iplayer on line try downloading iplayer desktop, then download the programmes you want to watch (usually the next day). I'm sure you realise that the jerky replay of iplayer online is because of an ISP issue (probably) not providing fast enough service.

I implemented the majority of recommendations from Milo and also downloaded iPlayer Desktop. There was an improvement, and when I ran that test it gave me 4 green ticks. Not sure whether the tick means 'good' or whether it indicates completion of that section?

Perhaps I picked a bad time, but my one attempt to download to the desktop looked like it was going to take 20 minutes to get a 1 hour programme, so I didn't bother.

You will NEVER find RealPlayer on my machine (or Norton, or Mc, or......)

If it is going to take 20 minutes to download a 1 hour programme I would be quite pleased! My trick when I need to use iplayer desktop is to set it downloading when I am ready for bed and I then have it available the following morning to replay, without interruption, when I wish.

P.P.