Actually server was expecting UTF-8 encoded vales for those characters instead of ASCII values. OP didn't provided actual stream page url to test with. the following command will work correctly with properly encoded characters.
ASCII => UTF-8
FC => C3 BC
F6 => C3 B6
Code:
rtmpdump -r "rtmpe://videodersane.uzaktanegitim.gen.tr/vod//mp4:video_ders_2013/soruc%C3%B6z%C3%BCm%C3%BC/gygk/t%C3%BCrkce/01.mp4" -W "http://videodersane.uzaktanegitim.gen.tr/Content/swf/StrobeMediaPlayback.swf" -o Test.flv
Code:
RTMPDump v2.4 GIT-2014-03-02 (Compiled by KSV)
(c) 2010 Andrej Stepanchuk, Howard Chu, The Flvstreamer Team; license: GPL
Connecting ...
INFO: Connected...
Starting download at: 0.000 kB
INFO: Metadata:
INFO: duration 7946.20
INFO: moovPosition 36.00
INFO: width 1024.00
INFO: height 768.00
INFO: videocodecid avc1
INFO: audiocodecid mp4a
INFO: avcprofile 100.00
INFO: avclevel 31.00
INFO: aacaot 2.00
INFO: videoframerate 14.98
INFO: audiosamplerate 44100.00
INFO: audiochannels 2.00
INFO: trackinfo:
INFO: length 119377990.00
INFO: timescale 15000.00
INFO: language eng
INFO: sampledescription:
INFO: sampletype avc1
INFO: length 351837422.00
INFO: timescale 44100.00
INFO: language eng
INFO: sampledescription:
INFO: sampletype mp4a
256.554 kB / 8.07 sec (0.1%)