There is a file size limitation in the default web.config. You can increase the file size easily. You may wish to adjust the timeout setting as well. Here are the default lines from the web.config for 4.3.2:
< !-- allow large file uploads -- >
< httpRuntime useFullyQualifiedRedirectUrl="true" maxRequestLength="8192" requestLengthDiskThreshold="8192"/ >
Change the maxRequestLength and requestLengthDiskThreshold to whatever you wish. The default timeout is in the machine settings but you can override it here. So here's an example, you could change it to this to allow 10 meg files with up to 20 minutes of time to upload:
< httpRuntime useFullyQualifiedRedirectUrl="true" maxRequestLength="10240" requestLengthDiskThreshold="10240" executionTimeout="1200" / >