As you found, the MWG is blocking this content (as can be indicated by a 403). In addition to the 403, the MWG will populate the "Block.ID" value. In this case it is at the end of the line (22).
This is a media type block. Each block id is set on the block page template, see below screenshot:
Hope this helps,
the screenshot you posted shows the action template (block informations) only. When I browse the youtube URL I don't see the block template site, just the player is not starting.
At the media block list there are some different media types listed and I cannot se what kind of media the MWG is blocking. The URL doesn't show me a file type. I don't figure out what it is.
How can I find out what file type is blocked?
I had same problem that some of youtube videos did not start to play. There were two reasons for that:
1) The connection was slow that video could not loaded, so I had waited to loaded all video once and replay again.
2) There was commercial at the video that my rule was blocking them in web gateway, which I had intended to do it.
Also you may look at coding results of the site. Some of the media players are redirecting to ad during the video stream. The redirected site inside of video might be blocked category in your web gateway ruleset.
The block page is sent to your browser, but the browser doesn't display it. Any easy way to see the block page is to run wireshark on your client and follow the stream where the block page is sent. You will see the raw html of the block page with whatever information you have configured on your block page templates.
For reference, youtube uses video/quicktime filetype and flash videos.
The slow connection is not the point. 100Mbit should be enough to load the video. The 2. point will be the more likely. At my tests I found out that most of the videos that got blocked had a commercial in front. I don't need to block the commercial.
Is there a possibility to see what is blocked at the debug functions of the MWG?
Wireshark is maybe an option, but I'm not sure that it works with this not so readable URL, see first post.
I figured out what kind of content was blocked.
At the end I done the wireshark troubleshooting way. It's indeed a good way, because, how you told, you see the html block site.
part of the wireshark packet:
<b>Filename: </b>videoplayback<br />
<b>Media Type (detected): </b>video/quicktime<br />
<b>Media Type (from file name): </b><br />
When you use the user-defined-logs you see the URL, but I is not clear to see what type of content get called.
Thanks foe all the informations.