From version 7.2, we have a new easy way!
You can open the file "server.xml", which should be in the path:
Linux: .. /123flashchat/server/etc/groups/default/
Windows: ..\123FlashChatServer7.3\server\etc\groups\default \
Then find the parameter below:
<audio-video outgoingBandwidth="12" selectedVideo="On" selectedHandsFree="On" needRequest="Off" video="On" selectedAudio="On" moderatorNeedRequest="Off" captureHeight="120" canShutOffAdmin="On" captureWidth="120" audio="On" adminNeedRequest="Off" maxWindow="5" canShutOffModerator="On" allowGuest="On" broadcastAudio="Off"></audio-video>
You can change
outgoingBandwidth="12" to change the video quality. Change
captureHeight="120" and captureWidth="120" to change video size.
Then save server.xml and restart the chat to enable. Have a Fun!