Parse video urls a little more robustly

Non-https urls and "youtube.com" (without "www") urls are now supported.

go/blog/blog.go

	"io/ioutil"
	"net/url"
	"os"
	"strings"
	"github.com/russross/blackfriday"
	"gopkg.in/yaml.v2"
		case "text":
			err = textTmpl.Execute(os.Stdout, post)
		case "video":
			if !strings.HasPrefix(post.URL, "https://www.youtube.com/watch") {
				exit(fmt.Errorf("can't handle video '%s'", post.URL))
			}
			u, err := url.Parse(post.URL)
			if err != nil {
				exit(fmt.Errorf("invalid video url '%s'", post.URL))
			}
			id := u.Query().Get("v")
			if id == "" {
				exit(fmt.Errorf("invalid video url '%s'", post.URL))
			if (u.Host != "youtube.com" && u.Host != "www.youtube.com") || id == "" {
				exit(fmt.Errorf("unsupported video url '%s'", post.URL))
			}
			post.URL = id
			err = videoTmpl.Execute(os.Stdout, post)