I have no way of knowing, but I suspect most people who use Blogger.com for their blogs, compose their posts within the Blogger online software. That’s what I did for several years before I discovered Windows Live Writer.
It comes as part of a suite of free software from Microsoft called Windows Live Essentials and gives me much more control over sizing and placing images and videos. If you’re using a Windows operating system and want to try it, you can check it out here. The suite also includes Windows Live Mail, which makes it a breeze to manage multiple email addresses.