continuous numbers

i want to change this:

this 1.jpg
this 1.mp4
this 1.webm
that 1.jpg
that 1.mp4
that 1.webm

to this:

this 1.jpg
this 2.mp4
this 3.webm
that 1.jpg
that 2.mp4
that 3.webm

can someone please show me how to do this if it's possible? thank you

Assuming that your example hasn't oversimplified the problem the jpg files are already correctly named and it is simply a matter of renumbering all mp4 files as 2 and all webm files as 3.

Use a List replace method with two entries...

1) Replace: 1.mp4 with: 2.mp4
2) Replace: 1.webm with: 3.webm

Apply to: Name and extension