I tried 3-4 sites and they all seem to be working well.
The only advice I can come with is that you should add some instructions or maybe change the text of the bookmarklet as I first thought it was a button.
I'll see if I can add some small text below the button which will make it more clear. Can I also ask which sites you tried it with?
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I'm eager to here other people's feedback on this as I'm looking to improve the service. Please leave a comment if there is anything that needs to be improved.
Thanks for the feedback!
The main benefit is that we have an improvised retriever which at the moment automatically extracts media (Flash/SWF..., Videos/FLV/MP4... and Audio/MP3/M4A...).
Can you please link to a file which youtube-dl supports and SaveItOffline does not? :)