It will delete {count, plural, =1 {1 video} other {<x id="count"/> videos}} uploaded in this channel, and you will not be able to create another channel or account with the same name (<x id="PH" equiv-text="videoChannel.name"/>)!
Enabling it will allow other administrators to know that you are mainly federating sensitive content.<x id="LINE_BREAK" ctype="lb" equiv-text="<br />"/> Moreover, the NSFW checkbox on video upload will be automatically checked by default.