Use on Arch Linux

In “Media playback Read Me.txt” it says both:
VLC can be used with both 32 and 64 bits versions of Linux. However, the
“bit-ness” of VLC and the Java environment must be the same. So on a
64-bit Linux it is best to use a 64-bit Java, because your VLC will be
64-bit.

and
Your Java must not be a 64bit JRE, but it is okay if your
hardware or Linux are 64bit

How? Then I have to set up a chroot or VM something?
Also, Arch does not have “update-alternatives” so that doesn’t help.

I currently can get no sound, is it because of the JRE? Otherwise everything works,but sound is kind of important for transcribing…

I think the second quote from the Read Me means to say that in principle it should be possible to have a 32-bit JRE and 32-bit VLC on a 64-bit pc. It is not a recommendation or so and I doubt if it will be the solution to your (no)sound problem.
I assume all sliders and check boxes in the Controls panel are in the right position to allow to produce sound (just to be sure) and that the application has permission to access the sound system etc.?
Are there any error messages in the log after loading a video or audio file (View->View Log…)?

-Han