Did it hurt?
If you had done this before, you would have avoided all this fuss.
Either post them in private, or do as I did, post a comment on the video with the link to the sound in question.
Someone called FunSoundTube has done a similar thing, but they have handled it much better. The attributions are in the videos themselves as well as in the descriptions: http://www.youtube.com/user/FunSoundTube/videos
Also as far as I can tell they are not offering download links that allow people to bypass the original sources here on freesound.
Regarding SEF: I received note from a user on these forums that one of my CC-BY sounds was uploaded to SEF on YouTube without attribution given in the video itself (CC-BY allows me to demand "reasonable" attribution in a medium and in-video text credits is more than reasonable). I will request deletion of the video and use YouTube's copyright complaint tool if not followed.
Here is the message that I wrote, in case any CC-BY 3.0 sound copyright holders would like to use it as a template to protect their rights:
Subject: Copyright infringement of my CC-BY 3.0 licensed sound on SEF YT Channel
The SoundEffectsFactory (SEF) YouTube channel contains videos of sounds to which I own the copyright, licensed under Creative Commons Attribution 3.0 Unported license (CC-BY 3.0) . The use of my sounds in these videos infringes upon my rights, in particular 4.b. of the license, which requires reasonable attribution/credits. For a video to contain text credits as part of the rendered video is completely reasonable. For a video to contain credits only in the text description is not sufficient.
You may only distribute videos of my CC-BY 3.0 licensed work that contain text credits inside the rendered video. YouTube annotations are not sufficient, instead the video has to be rendered with full attribution inside of it. The text has to be displayed either for the duration of the entire video or for a duration that allows an average reader to read the entire attribution (250 - 300 words per minute ). The font has to be well readable regarding foreground/background color and font size. The full credits have to be placed in the video description with direct, clickable links as well. All other terms of CC-BY 3.0 have to be adhered to.
Please delete all videos that contain CC-BY 3.0 licensed sounds, to which I own the copyright and do not upload any videos with CC-BY 3.0 licensed sounds, to which I own the copyright unless they adhere to the terms explained above and the CC-BY 3.0. Again, note that adding YouTube annotations is not sufficient.
Here is a list of affected videos that I was able to find:
If there are any other videos with CC-BY 3.0 licensed sounds, to which I own the copyright, please delete them as well and do not upload any videos with CC-BY 3.0 licensed sounds, to which I own the copyright without adhering to the terms explained above and the CC-BY 3.0.
Please note that I will recommend to request the same attribution to copyright holders of CC-BY 3.0 licensed sounds that I discover being used in an infringing way.
Please note that in case deletion of the infringing videos does not occur within 48 hours after this message has been sent, the infringement of my copyright on the SEF channel will be directly reported to YouTube via their copyright notice forms
Please note that for time limitation reasons, future infringement of my copyright on the SEF channel will be directly reported to YouTube via their copyright notice forms.
Please note that I am merely protecting my rights to avoid spread of my CC-BY 3.0 works being used in a manner that infringes upon my rights.
If you're having trouble finding your works in videos on the SEF channel that infringe upon your rights, try your nameo or username as a search term in http://youtube.com/user/SoundEffectsFactory/search
That seems really interesting, has it worked?
And also thank you for your effort with this!