With the benefit of hindsight using the keyword "robbery" on a video posted on YouTube was not the brightest idea. Including crystal clear shots of the face of a youth just before he committed his crime was also, probably, a mistake.
In fact the 19 seconds of film, captured on a mobile phone and showing the robber, his friends, the theft and the escape, provided police with all the evidence they would ever need. Today the footage made by a group of Welsh hoodlums as one of their number snatched a charity worker's spectacles landed the culprit in a cell.
The clip, recorded on Saturday on Wrexham's main shopping street, shows a teenage man in a white T-shirt walking in front of a group of around four friends all filming him on their phones.
The youth looks back at the camera and grins as he approaches a middle-aged charity worker as she talks to a group of potential donors. In the film he is shown reaching out and snatching the bemused woman's glasses before sprinting off down the pedestrianised street. The final shot shows one of the group still filming with a smile on his face as those around him guffaw with laughter.
The clip was posted two days ago by "wxmboys" and titled "Wild specs robbery" and captioned: "pissed up bald lad steals randomers specs in street! Absolutely WILD!!!"
Wxmboys put it online as "comedy" but within hours of the arrest the posting, which had been left on the video-sharing website in the hope of impressing other users, instead quickly attracted a stream of derision.
With those responsible variously branded "cretins", "chavs", "scum" and "retarded" one user commented: "Who's laughing now, losers? I bet your parents are proud."
North Wales Police confirmed that a spectacles theft was reported in Wrexham on Saturday and that they were tipped off about the footage by a member of the public within hours of it being posted yesterday,
After viewing the film officers were able to identify the culprit and a police source said officers had recovered a pair of spectacles after visiting his home.
The source said: "We had a word with him - he isn't the brightest lad."
A force spokeswoman said: "We have arrested an 18-year-old man from Wrexham on suspicion of theft. We were told about the existence of the footage and after officers viewed it we were able to follow new lines of inquiry which resulted in the arrest. The spectacles have been recovered."
Unfortunately the video has been removed from Youtube