Both apt and snap version of Okular crashe with audiovisual content

Hi,
I have been trying to use both the apt and the snap version of okular in Ubuntu 18.04 to display presentations created with latex/beamer that include audiovisual content. The apt version works fine as long as I do not exit the presentation mode. Every time I exit presentation mode it crashes with the following message:

pa_write() failed while trying to wake up the mainloop: Bad file descriptor
pa_write() failed while trying to wake up the mainloop: Bad file descriptor
pa_write() failed while trying to wake up the mainloop: Bad file descriptor
Assertion 'pa_close(fds[1]) == 0' failed at pulsecore/core-util.c:2647, function pa_close_pipe(). Aborting.

The snap version is even worse: every time I try to play audiovisual content, okular crashes with a long list of messages like this:

ALSA lib conf.c:3916:(snd_config_update_r) Cannot access file /usr/share/alsa/alsa.conf
ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM default
[000055e08eacc8d0] alsa audio output error: cannot open ALSA device "default": No such file or directory
[000055e08eacc8d0] main audio output error: Audio output failed
[000055e08eacc8d0] main audio output error: The audio device "default" could not be used:
No such file or directory.
[000055e08eacc8d0] main audio output error: module not functional
[00007f1e7c1a4360] main decoder error: failed to create audio output
[00007f1e600a56f0] main video output error: video output creation failed
Segmentation fault (core dumped)

An example pdf can be downloaded from here: https://github.com/giampierosalvi/slides_with_video

Anyone who knows an easy fix? I mean without waiting for a new version of okular?
Thank you!
Giampiero