Sure: you likely don't want to be dealing with large files on Lambda. Why?

* The maximum timeout window for a function invocation is 300 seconds

* The maximum available temp disk space per instance is 500MB

* Memory is maxed at 1.5GB

In the function invocation time window you need to:

* retrieve the file (to memory or disk)

* transcode the file (outputting to memory or disk)

* upload the file (as the disk is not persistent)

This along with the following facts make it infeasible:

* transfers from S3 are fast, but non-s3 sources are likely to be much slower.

* assuming you mean large as in GB - you have nowhere to put the files (disk too small, memory too small).

* transfers to S3 are fast, but uploading the transcoded video to a non-s3 source will likely me much slower.

Hope that helps.