Just remove the height and width options from \includemedia. Since there is no text-box argument (last-but-one argument), the video box will have zero size and be invisible. In order to be able to start playing the sound, you will have to specify a combination of activate=pageopen option (done already) and autoPlay=true FlashVar.
APlayer.swf can only play MP3 sound files.
If you want the sound to be played on the cover slide, then you will have to insert it there: \frame{\titlepage\includemedia...}.
Video and sound files are embedded as part of the PDF and don't need be distributed along with the PDF.
Slow down of page transitions may occur because AdobeReader has to uncompress and load the embedded media files and players while opening a page with embedded media.
If you just want to start playback of a sound file when the PDF is opened and let it play for the remaining time of the presentation, embed it on the cover page (see above) and use option deactivate=onclick. This suppresses un-loading of the media when the cover page is left during the presentation.
You fill the JavaScript console with as many VIEW sections as you want, by manipulating the model to your liking and then selecting 'Get Current View' from the context menu. This requires \includemedia option 3Dmenu.
Copy the console content and paste it into a text file, say myviews.vws, opened in a text editor of your liking. Edit the file, giving meaningful names to the generated views, e. g. VIEW=First View etc.
Now edit your *.tex file to make use of myviews.vws and to insert media buttons:
\includemedia[
label=my3dobject,
3Dviews=myviews.vws,
width=4cm,height=4cm,
3Dmenu,
...
]{click!}{something.u3d}\\
\mediabutton[3Dgotoview=my3dobject:(First View)]{\fbox{First View}}
\mediabutton[...]{...}
Finally, when you are done, option 3Dmenu can be removed.
See, e. g. the example in Fig. 7 of the media9 documentation.
Best Answer
Update:
Current versions of Acrobat Reader DC allow users to add new 3D views at runtime and to save them with the PDF file. Adding new 3D views does not require recompilation of the PDF from the TeX source anymore.
No, this is not possible in AdobeReader.At runtime, a user may manipulate the 3D object in AdobeReader and produce new
VIEWsections via the context menu (mouse right click), provided the3Dmenuoption was set during compilation of the PDF. He can addVIEWsections to an existing or to a blank new views-file (via copy/paste from the JavaScript console) and associate the modified views-file with the u3d/prc file via option3Dviewsduring the next LaTeX run.Thus, the user needs the complete LaTeX document source plus the u3d/prc files to be embedded and recompile the whole thing with the new view added.
Note that JavaScript cannot write to files directly, for security reasons.
The views-file is not embedded verbatim into the document, but parsed by LaTeX and translated into PDF objects when compiling the LaTeX document source.