Refactor RegularLink image & video handling

org/testdata/example.html

@@ -162,7 +162,22 @@ regular link <a href="https://example.com">example.com</a> link with description
 </li>
 <li>
 <p>
-regular link to a file (image) <img src="my-img.png" alt="file:my-img.png" title="file:my-img.png" />
+regular link to a file (image) <img src="my-img.png" alt="my-img.png" title="my-img.png" />
+</p>
+</li>
+<li>
+<p>
+regular link to a file (video) <video src="my-video.mp4" title="my-video.mp4">my-video.mp4</video>
+</p>
+</li>
+<li>
+<p>
+regular link to http (image) <img src="http://www.example.com/my-img.png" alt="http://www.example.com/my-img.png" title="http://www.example.com/my-img.png" />
+</p>
+</li>
+<li>
+<p>
+regular link to https (image) <img src="https://www.example.com/my-img.png" alt="https://www.example.com/my-img.png" title="https://www.example.com/my-img.png" />
 </p>
 </li>
 <li>

org/testdata/example.org

@@ -58,7 +58,11 @@ this one is cheating a little as tags are ALWAYS printed right aligned to a give
   1. regular link [[https://example.com]] link without description
   2. regular link [[https://example.com][example.com]] link with description
   3. regular link to a file (image) [[file:my-img.png]]
-  4. auto link, i.e. not inside =\[[square brackets]\]= https://www.example.com
+  4. regular link to a file (video) [[my-video.mp4]]
+  5. regular link to http (image) [[http://www.example.com/my-img.png]]
+  6. regular link to https (image) [[https://www.example.com/my-img.png]]
+  7. auto link, i.e. not inside =\[[square brackets]\]= https://www.example.com
+
 ** blocks
 #+BEGIN_SRC bash
 echo a bash source block