After reading of similar issues, switching to "Remote" should help a lot.
"rtsp://user:pass@ip:554/h264Preview_01_main" works well on ffmpeg and in VLC (VLC without smearing).
Now i have switch to "remote" and give data as follows:
Remote Protocol: RTSP
Remote Method: RTP/RTSP
Remote Hostname: user:pass@ip
Remote Hostport: 554
Remote Hostpath: /h264Preview_01_main
It results in 404 Stream not found

I have try the Hostpath with and without starting backslash with same results. A backslash at ending of hostpath results in 404 and 400 error.
A try with my 2MP Foscam give me not a 404 error but a 400 error (Bad request)
Any ideas?