Otherwise as suggested, this has nothing to do with template hierarchy. These templates that you are mentioning is purely for use with post formats. I qoute from the codex
Post Formats is a theme feature introduced with Version 3.1. A Post Format is a piece of meta information that can be used by a theme to customize its presentation of a post.
When a post is created/written, the author has option of available post formats in the post format meta box (if that feature is enabled and a post format has been registered) . Example, if you add a post with a video, you can choose the video post format when creating your post. Your post will now be displayed using the ‘content-video.php’ template.
Coming back to your question, you can simply just select the “Standard” option from the post format meta box when you create a post. If you add a post with a video, and you select the “Standard” option, your post will be displayed using ‘content.php’, and not ‘content-video.php’ You really don’t have to use post formats if you don’t want to.
Just one last point of note here. Don’t make changes to a theme that you’ve downloaded and that you are not the author of. The BIG reason been, if you make changes to that theme, and you upgrade that theme in the future, you will loose all your hard work. ALWAYS ALWAYS create a child theme for such themes
EDIT
One point I forgot to mention, remember, the_excerpt() strips all shortcodes and HTML tags, so your videos and audiofiles won’t be displayed if you use the_excerpt()