You tell us. Potentially employ Wireshark to see what gets transferred over the network, if the HTTP Live Headers aren't enough.

Ok, so here's the dump of relevant packets from Wireshark:



*$EY@gJ!?P"YP\3POST /webappUpload/49930-499301239320229 HTTP/1.1
Cookie: vis=p0BuJAXf0OBO3FMD9obUFbycSoTX3TUD2XOyO7aGCTzzjo5WsNn86yr5Tt
+b10Ylyk6Nu3/ua4bzpmQmspZghGkXehIQnCk0bqQNm0lXV4jN5CyU5lNyltxXJNJjr62l
+0GlVpNf9s2Ic=; __utmx=185998783.00002873392993216020:1:0.000035877605
+79199214:3:1.00003589672086876198:4:1; __utmxx=185998783.000028733929
+93216020:1238293709:2592000.00003587760579199214:1239319412:2592000.0
+0003589672086876198:1239319661:2592000; __utma=185998783.444999910131
+1638000.1238293710.1239163691.1239318674.6; __utmz=185998783.12382937
+10.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __qca=118505064
+2-48687324-6578781; gpermlogin=+Q1/fMvu4oPYsMY2dJwoGMiOqJPYNTxwCJZPMu
+BUCYCz6KI5fsHldCTiIYfqFCXh; __utmv=185998783.Member; _csuid=47196f595
+1870bda; JSESSIONID=EFDC78AE4E5626E4A69BC7D37D7DC767; JSESSIONID=EFDC
+78AE4E5626E4A69BC7D37D7DC767; JSESSIONID=EFDC78AE4E5626E4A69BC7D37D7D
+C767; gathersid=www07; ref=direct_www; __utmb=185998783.10.10.1239318
+674; __utmc=185998783; __qcb=777367231
Referer: http://www.gather.com/shareVideos.action
Cache-Control: no-cache
Connection: Keep-Alive
Accept: */*
Accept-Encoding: text/html
User-Agent: Aurigma Image Uploader JE
Host: media-upload.gather.com
Content-Length: 761879389
Content-Type: multipart/form-data; boundary=XpK3v82IExIWz9o2ChOlFCPaY8
+F5QqDQ3j7y5

--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-d

*$EY@gJ!?P"^jP\0ata; name="memberId"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

49930
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="contentType"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

video
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="albumId"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it


--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="uploadSessionId"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

499301239320229
--

*$EY@gJ!?P"hP\2SourceFileCreatedDateTime_1"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

2009:03:27 04:46:35
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="SourceFileLastModifiedDateTime_1
+"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

2009:03:27 04:46:35
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="SourceFileCreatedDateTimeLocal_1
+"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

2009:03:27 00:46:35
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="SourceFileLastModifiedDateTimeLo
+cal_1"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

2009:03:27 00:46:35
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="FileName_1"
Content-Type: text/plain; charset=UTF-8; Content-Transfer-Encoding: 8b
+it

Exported.avi
--XpK3v82IExIWz9o2ChOlFCPaY8F5QqDQ3j7y5
Content-Disposition: form-data; name="SourceFile_1"; filename="Exporte
+d.avi"
Content-Type: video/x-msvideo; charset=UTF-8; Content-Transfer-Encodin
+g: binary
[download]



Here I'm trying to upload a video called Export.avi. I can definitely see that it's sending something, but not sure how to duplicate this POST request in Perl in order to actually send along the file.

HTTP::Request? Possibly even HTTP::Request::FromTemplate, although I've never tested it with POST data. Possibly you can also trick WWW::Mechanize into allowing you to set the Content-Type of the file. WWW::Mechanize not setting the Content-Type might or might not be construed as a bug.