My validation is preventing other things from uploading - ruby-on-rails

Question

In my app a user can upload a picture(with paperclip) or a link from youtube. The link is able to be submitted but now when I try to upload a picture I get a validation error saying the link is invalid. I have been going after this for like an hour now and I'm just going in circles at this point, any help would be awesome.
post.rb
class Post< ActiveRecord::Base
belongs_to :user
validates :user_id, presence: true
YT_LINK_FORMAT = /\A.*(youtu.be\/|v\/|u\/\w\/|embed\/|watch\?v=|\&v=)([^#\&\?]*).*\z/i
validates :link, allow_nil: true, format: YT_LINK_FORMAT
before_create :set_content_type
has_attached_file :pic, :styles => { :thumb => "600x600#", :medium => "300x300#", :small => "160x160#"}
validates_attachment_content_type :pic, :content_type => ["image/jpg", "image/jpeg", "image/png" ]
def set_content_type
self.is_pic = !self.pic_file_name.nil?
self.is_link = !self.link.nil?
# parse link
if self.is_link
uid = link.match(YT_LINK_FORMAT)
self.uid = uid[2] if uid && uid[2]
if self.uid.to_s.length != 11
self.errors.add(:link, 'is invalid.')
false
elsif Post.where(uid: self.uid).any?
self.errors.add(:link, 'is not unique.')
false
else
get_additional_info
end
end
end
Post_controller.rb
def create
#post= Post.create(post_params) do |post|
post.is_pic = true if params[:post][:pic]
post.is_link = true if params[:post][:link]
end
#post.user = current_user
respond_to do |format|
if #post.save
format.html { redirect_to #post, notice: 'post was successfully created.' }
format.json { render json: #post, status: :created, location: #post}
else
format.html { render action: "new" }
format.json { render json: #post.errors, status: :unprocessable_entity }
end
end
end
The form
<%= form_for #post, :html => { :multipart => true } do |f| %>
<% if #post.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#post.errors.count, "error") %> prohibited this post from being saved:</h2>
<ul>
<% #post.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="uploads">
<h3>Upload Photo</h3>
<div class="visible-xs">
<%= f.file_field :pic %>
<h3>YouTube Link</h3>
<div class="visible-xs">
<%= f.label :link %>
<%= f.text_field :link, required: false %>
</div>
<div class="center">
<%= f.submit :class => "btn btn-info" %>
</div>
</div>
<% end %>