Using 2.7
On w10
File is mpg
Copy Mode
I set the A and B markers on the 3 sec to remove from the beginning of the file.
I use the up down arrow keys to ensure that the B marker is on an I frame.
After setting B maker, Save with output set to Mpeg-PS ff
I get the following errors as seen in Attachments 1 - 3
Thanks .....
SUE= Stupid User Error.....file was mp4 not mpg ........ working as expected....