stuff.rb

  def usertags
    if params[:tags] != nil
      @tags = params[:tags]
      session[:tags] = @tags
      @videos = Video.tagged_with(session[:tags]).order("views DESC").page params[:page]
    else 
      session[:tags] = nil
      @videos = Video.order(views: :desc).page params[:page]
    end
    respond_to do |format|
      if session[:tags] == nil
       redirect_to videos_path, notice: 'Tags have been cleared.'
     else
       format.js
     end
   end
 end