I was skeptical about this plugin because it hasn't been updated in over a year but I thought I'd give it a try anyway since it appears to be the only free plugin for creating video sitemaps.
I generated the sitemap and submitted it to Google but I received an error saying the sitemap was an HTML page, even though the file extension is xsl. When I tried to open the file in my spreadsheet app (OO Calc) it gave me a general input/output error.
The developer website states that the plugin should generate an xml file in a particular location but it didn't.
UPDATE: I am changing the rating for this plugin based on a fix I discovered.
If you are having the problem I described above and are using W3 Total Cache try this adjustment:
In W3TC, create an extra user agent group. Under Performance and then User Agent Groups click “Create a group.” Name the group (e.g., “Google” or “Googlebot”). In the user agents field enter “googlebot” (without the quotes). This will force W3TC to make a separate cache for Googlebot user-agents, which appears to have solved my problem.
If you're also using Yoast SEO to create your XML sitemaps, this may or may not create a conflict with Google XML Sitemap for Videos. So far it hasn't for me but I'll be monitoring it.