Not sure whats different to 3.41 as it says the same updates in the readme as before!!
Prob worth installing for safety.
XAVC/XDCAM Plug-in for Avid 3.42 Update
•Avid Media Composer v7.0.4.4 and v8.4 support.
•Improvement of XAVC Long GOP playback performance.
•Support for native XAVC-I implementation in Avid Media Composer v8.3.1 and v8.4.
•Support for Spanned clips in Avid Media Composer v8.3.1 and v8.4.