Enough with people reuploading others' stuff on their own Youtube channels.

youtube_cleanser.js

badChannels = ["gamehelper", "gamerspawn", "machinima", "vaivecorporation", "loquendoitalia", "patron500", "jon3pnt0"]

$(jQuery.grep($(".video-list-item, .result-item, .result-item-main-content, .sidebar-ads, .yt-tile-default"),
  function(item, number){
    //filter regular videos
    username = $(item).find(".yt-user-name").text().toLowerCase();
    console.debug(username)
    if(badChannels.indexOf(username) != -1) return true;
    
    //perhaps it's an ad.
    username = $(item).find(".ads-by a").text().toLowerCase();
    console.debug(username)
    if(badChannels.indexOf(username) != -1) return true;
    
    return false;
  })).css('opacity', 0.1);

//Why not hide it entirely? For example, on your homepage these things come with an handy ",

//perhaps it's a related channel ad thing

$(jQuery.grep($(".related-channel"),
  function(item, number){
    //filter regular videos
    username = $(item).find(".title").text().toLowerCase();
    if(badChannels.indexOf(username) != -1) return true;
    
    return false;

  })).css('opacity', 0.1);

//perhaps it's one of the videos featured at the end with the HTML5 player. Unfortunately I will need to poll for these ones apparently. These are much more in your face, though, so let's be harsher with these ones.

setInterval( function(){
$(jQuery.grep($(".videowall-still"),
  function(item, number){
    //filter regular videos
    username = $(item).find(".videowall-info-author").text().toLowerCase();
    if(badChannels.indexOf(username) != -1) return true;
    
    return false;

  })).remove()

}, 1000);

//perhaps we are on this guy's page, even. Let's do something about it.

var username;
try {
  username = document.getElementById("watch-userbanner").title.toLowerCase();
} catch(e) { //ugh, what's next is totally unreliable
  username = $("#watch-headline-user-info .yt-uix-button-content")[0].innerText.toLowerCase();
}

if(badChannels.indexOf(username) != -1){
  if(confirm("You flagged this channel, " + username + ", as bad. Search another such video instead?")){
    videoTitle = document.getElementById("eow-title").innerText
    window.location = "http://www.youtube.com/results?search_query=" + escape(videoTitle)
  }
}

👍