The idea behind Tag Recordings is that you as a GA user can record a journey through your website and then look at how GA would process the GA hits. This lets you validate that your site works correctly with GA. If there's an issue, you can troubleshoot it on the spot, make changes --for instance to the GA configuration-- and instantly see the effect of your changes.
Here is a 2 minute demo:
Here are 8 things you perhaps didn't know about Google Tag (Assistant) Recordings:
To use Tag Recordings, you need to have a recording of a journey through your website. The recording is in the form of a HAR. The easiest way to record is to use Google Tag Assistant: just hit the record button. But you can also use the record functionality in the Chrome Devtools. You can also use Firefox or IE or construct your own HAR.
2. Dropped hits? Check hit parse errors!If you make an error in --for example-- the number format of an event sent from your web page, the hit will be rejected when it arrives at google-analytics.com because the hit cannot be parsed. Example:
ga('send', 'event', 'cat', 'act', 'lab', 5.2);
This fails to parse in the GA server because the last parameter must be an integer. The parse error does not make it back to your web browser, so you don't know that your hit will never make it into any reports.
While Tag Assistant does not show the error (it only does a small set of validations in the browser itself), Tag Recordings however does show the parse error: it uses the same code that the Google Analytics server uses.