I am embedding my youtube videos and they show no problem in the previews of my newsletter but now when I do test emails. Any help greatly appreciated as I want to keep them in.
All the best
I was just replying to you via support as well, but for anyone else...
Unfortunately, video just doesn't work terribly well in email. Many email clients strip out videos completely. Your best bet would be to take a screenshot of the video and link that to it hosted online instead. So the video would load in the browser instead of an email client, where it will be better supported. You can put a little play button on the screenshot, something along the lines of what Wisita does which tends to encourage clicks.
Or you could try using HTML 5 to embed your image. It would work in a couple of email clients and fall back to an image in the rest.