ownership of work

Ok problem as follows. I've done few projects for a local public body, editing, filming, authoring to DVD. The final product to the company has usually been 20 DVDs. They have from time to time asked me for further copies which i supplied free of charge.
I recently got a call from a teccie in their office telling me he was 'ripping' one of those DVDs to extract the footage so they could put it on their website. No, not even the courtesy of asking me first. I stayed off my high horse and asked him what he wanted. Told me he "Can't do it, do you know how to do it ? Can you help me, how do I do it, think I need it to be FLV". Eventually conceded he was just fiddling and didn't really know what he was doing. Because I wanted to ensure that whatever he did would be of an appropriate standard I offered to do it myself free of charge and deliver an flv to his site designers. I want my work to look good on the web even if I have to do it myself.
I then emailed his boss, didn't complain, stayed off my high horse, very politely suggested that this work shouldn't be handed to someone who admitted he was incapable of doing it, volunteered to make whatever copies they wanted.
'Boss' was incensed that I had the gall to suggest how she ran her office, instructed that I wasn't to be used for any further video work!!!!
OK I have to swallow that but have now discovered that they have a UTUBE account where they advertise their service ( they offer a range of youth/community related opportunities/training etc.) They have uploaded this 'ripped' copy and removed the credits at the end which attribute the authorship to me.
I need advice lads, where do I stand with ownership of the original DVD, can these people do what they want with this work, ie make unauthorised copies, post them on their site, doctor them to remove my authorship credits?
I need to know where I stand before digging my heels in.
Hope some of you might be able to advise me or point me to a relevant body. I'm in the UK.
Peter

peterdewolf@picurpicture-multimedia.co.uk