I honestly don’t find it logical to embed videos on blogger from external sources and then publishing them through blogger. How can your site appear on search results page when the video you shared is hosted by someone else. Google will instead show results from the actual server instead of displaying your site on SERPs.
Take for instance you share youtube videos, Google crawls youtube faster than any webpage which is simply embedding youtube videos, Google will keep such sites at low priority and will instead send all traffic to the actual youtube page.
Creating a video sitemap makes sense only when you selfhost raw video on your site and deliver video content yourself instead of simply sharing videos from external sources.
A video sitemap is created by containing the following information for creating a mRSS feed:
- Play page URL
- Thumbnail URL
- Raw video file location and/or the player URL (SWF)
This is possible when you create a XML file using PHP or ASP.net. Currently blogger does not provide database access, so in short as @MUHSIN_MOHAMED_PC suggested, you can instead create a site on wordpress and then create Video sitemap using a php plugin but it is not possible effectively on Blogger at present, templates which support video Embedding are not properly coded in terms of SEO and using them is never wise.