Firstly, I don't think the dashcam footage has been released by police, it was obtained by the Daily Mirror.
Secondly, if the police thought there might be forensic evidence it would take a few days to come back from the lab. As they can only suspects for 96 hours max without a charge, and the lab tests would take longer, it would make more sense to release them.
Additionally, while the house was empty as both residents were in the cells briefly, the police might well have placed a bug, maybe colluding is exactly what they wanted to hear, maybe that's why PE got nicked. Maybe!
Finally, for the benefit of new members and those in the USA who are working this case, this article explains the BIG differences between English and American arrests. I've rolled this out before but I think it's really important for posters who sleuth cases in both countries.
......because it’s a lot easier to arrest someone in the United Kingdom, but being arrested there isn’t a big deal like it is in the United States. American police need probable cause to make an arrest, but in the United Kingdom, officers can arrest on suspicion. Probable cause is defined as the belief that a crime was probably committed, and that the suspect was probably responsible. To have probable cause, greater evidence is required. Reasonable suspicion means that a right-minded individual would have grounds to suspect that a crime had been committed and that the suspect might be responsible.
http://www.slate.com/articles/news_..._is_being_arrested_different_in_britain_.html