Thanks for sharing, this was the most helpful video that I've found on the topic when using the gtm4wp plugin to propagate the enhanced ecommerce data to FB pixel. I don't know if there's some other pre-processing of the GTM CJS variable going on inside the GTM FB TAG, the presenter doesn't show it but you can see throughout the video that in GTM / Variables the "return type" is "Array" and it worked perfectly for him. For me this didn't work because FB Event Manager is expecting a Json object and not an Array, my event was properly recorded by FB Event Manager as a "ViewContent" event but without the "CUSTOM PARAMETERS SENT" portion. I fixed this by modifying the variable "CJS - FB - ViewContent - Contents" to explicitly return the first array element ([0]) of {{DLV - ecommerce.detail.products}} which is the actual object and it worked. For my implementation I'm using "Facebook Pixel by facebookarchive" TAG. I'm looking forward to more content like this.