1) This is known ALSA bug. You can try export PULSE_LATENCY_MSEC=60 in terminal before running Toxygen. Or try solution like this
2) Video calls is not yet implemented. One bug stopped implementing this feature for a while
I'm closing this as not really client issue
When in-call, I only hear a kind of buzzing sound, and I get this message repeatedly in the output:
Running Arch Linux, built from AUR package. Also, video calling doesn't seem to work.