problems with filters

[record]

hello, good morning,

i have installed avidemux and tried to edit a downloaded video BUT filter button IS NOT available.
it remains "grey" and i can't use it, both audio and video.

is there anyone who can explain me why?
it is a video downloaded from youtube.
it is "the end of the world" by discovery channel, about stars and solar system.

thanks for help.

[eumagga0x2a]

Filters are not applicable in copy mode, thus the button is disabled instead of presenting an error message to the user later in the process. Select a codec to enable it.

[record]

many thanks!!!
i'll try this.

FOUND THE CODEC!
THAAAAAAANKKKKKSSSSSS!!!!!!!!!!!