Seperating Words To Different Cells

I have hundreds of file names, and to cut a long explanation short, they are exported as a CSV file to excel. In order indentify the owner of the file I need to rename the file with a commar where you see the dash or the underscore in order to have the name appear in the next cell, as can be seen with Syma and Kevin below, so I can then sort the columns etc etc.

I know there is a formula that I can use to achieve this, ie have syma.pdf and kevinc.pdf in the next cell.

I think it works on identifying how many characters along the name and then send i to the next cell.

as you can see below, there is no set amount of characters to put into a formula.

Could I say, for example, if after dash /underscore put next word in next cell?

t5 mon a2 w6-syma-0003.pdft5 mon cst w2_dellwynneh.pdft5 mon a23 w3_MASUMS.pdft5 mon cmn201a w1- syma.pdft5 thurs wiabe w2_kevinc.pdft5 thurs wiabe2 w2_kevinc.pdf