Give a name to the video template

This is useful for debugging.

go/blog/blog.go

@@ -417,7 +417,7 @@ var textTmpl = template.Must(baseTmpl.New("text").
</article>
`))
var videoTmpl = template.Must(baseTmpl.Parse(`
var videoTmpl = template.Must(baseTmpl.New("video").Parse(`
<article id="{{ .Id }}" class="video">
	{{- template "title" . }}
	<iframe width="560" height="315" src="https://www.youtube.com/embed/{{ .URL }}" frameborder="0" allowfullscreen></iframe>