Trim Editing with H.264 Encoder

Hello, we have a ATEM/2 and a H.264 encoder and we are using it to capture the sermon in our worship service. I would like to trim edit the video as quickly as possible to get the file uploaded to Youtube and Vimeo. Will media express do this? If so, how? I find the docs a little lacking. A quick screen cast of the basics for us Production Newbies would be awesome.
Thank you very much for the audio mixer in 3.2.
Thanks for your help in advance.
John
Thank you very much for the audio mixer in 3.2.
Thanks for your help in advance.
John