Fix or better explanation

[knauso]

Hi,

I had a few minute struggle with this until I realized what the issue was.

If this is the shortcode:
[youtube width="800" height="500" video="M7lc1UVf-VE"]
Then this needs change:
{% include 'shortcode-render' render:'src' default:'M7lc1UVf-VE' %}
It should be:
{% include 'shortcode-render' render:'video' default:'M7lc1UVf-VE' %}
OR
you can simply change instructions to:
[youtube width="800" height="500" src="M7lc1UVf-VE"]

Btw, thanks for this, it is making Shopify dev easier :)