Tumblr doesn't primarily market itself as a video uploading site, so it shouldn't be surprising that it doesn't have the versatility that other websites like YouTube or Vimeo have. Tumblr does support video uploads, but limits the format to MP4 videos only. Each person is also limited to 5 minutes of video each day, and each file must be 100MB or smaller in size. Of course, if you upload video to another website, there is no limit on what you can share on Tumblr.
Supported Video Formats
If you want to upload your own video to Tumblr the same way you would upload an image, you will need to make sure your video is in MP4 format. For video uploads, Tumblr doesn't support any other options. Specifically, MP4 format videos must use the H.264 codec and AAC audio; this is the default setting on most MP4 videos so in most cases you shouldn't have to worry about that. This is the same format supported by Apple's iPhone, so if your video software offers an Export to iPhone option, it should work on Tumblr.
If your favorite video recording software doesn't already support MP4 video, you can convert the video yourself using a free software or online conversion service like Handbrake, Videora or Any Video Converter (see Resources). Remember to keep your video files to less than 100MB and no longer than 5 minutes each, otherwise Tumblr won't process your video. Keeping your videos short has the added benefit of keeping your viewers on your blog without becoming distracted.
Using Linked Videos
There is no limit to how many videos you can post to your Tumblr blog, provided the videos are hosted on other websites. For example, you could upload 100 videos to YouTube, Vimeo or Dailymotion and then embed each of those videos into your Tumblr blog. As long as the video works on the website you chose, it should display without any problems on Tumblr. Most of these websites offer an easy-to-use embed code for sharing on Tumblr or other social media websites.
Not quite videos, but not simply images either, Tumblr treats animated GIFs separately than videos. As with other image files, there is no restriction on how many animated GIFs you can upload to Tumblr, but the file size for each GIF is limited to 1MB. If your video is extremely short, an animated GIF may be preferable, especially if you have to convert the video from a MOV or WMV format anyway. As with video conversions, there are several online resources for converting video to animated GIFs (see Resources).