Audio and video is using basic Windows functions to be able to ensure most users can run it. To help make sure everything is good though download the K-Lite Codec Pack from http://www.codecguide.com/download_k-lite_codec_pack_standard.htm
If it gives you any pop-ups saying it wants to fix something, click Yes. Run this, you might need to restart your PC or LB and see if that fixes it.
CriticalCid also created a tutorial on how to update MAME roms:
https://www.launchbox-app.com/forum/emulation/best-practice-for-keeping-mame-roms-up-to-date/page-2#p11536
Give that a read and grab the software. I just did it this morning after getting 400GB of MAME Rom's. I know a lot about Emulation and LaunchBox, it's my job, but I can't dedicate my time every day to something so it is really awesome when someone like Cid, who already did all this, shares with us.