If you are crawling large files in SharePoint 2013, you will see the following warning in your Search Logs.
“The file reached the maximum download limit. Check that the full text of the document can be meaningfully crawled”. If you want to avoid this and crawl the large files you must increase this limit.
The default Download limit for crawler is 64MB. You have to increase it to allow the crawling of videos. Its a bit tricky decision. I hope your videos are not Blueray DVDs converted to Mp4. The max is 1024MB which you can set using PowerShell. Review the video files and decide what size you must specify
$searchapp = Get-SPEnterpriseSearchServiceApplication
#this command is just to check the current value; default is 64
#where you replace <value> with the download limit; for example, 256
Now Run a Full Crawl. Crawl might take extra time but will reduce the number of errors.