Make certain you have "telnet" disabled when configuring the connection to the robot from TeraTerm.

There's JTAG and direct serial interface, but this shouldn't be causing a problem if you're normally able to connect and receive video.
 
Are you selecting XMODEM-CRC or XMODEM-1K protocol ?  I don't remember the options on TeraTerm.

Well ... I'm stumped.  If you have a good connection for video feeds, then the comm setup should be good.  Within TeraTerm, if you have "telnet" disabled and XMODEM-CRC selected, you shouldn't be having problems.

Are you connecting to port 10001 ?
 
The only real alternative is a JTAG cable.  You can go through the serial uart boot mode process, but that still has an XMODEM transfer component.

No.  The connection from host computer to Blackfin is just pass-through on the Matchport.
 
We use XMODEM transfers ALL the time without problem.  Maybe you can try the transfer from a different system.  If you have Mac or Linux, you can use the lsz command for transfer, as described here -  
    http://www.surveyor.com/blackfin/SRV_setup_bf.html#setup3

Also, you can use scripts with TeraTerm. For me, upload of firmware to SVS takes few seconds and one click at bat file.

I am using bat file for compilation of firmware and uploading to SVS if compile succeed.
 
I have two files:
C:\SRV\svs1_compile_and_flash_ldr.bat
C:\SRV\svs1_flash.ttl
 
A. "C:\SRV\svs1_compile_and_flash_ldr.bat"
It makes:
1) compile sources
2) copy firmware file to "C:\SRV\svs1.ldr"
3) upload it to SVS using TERATERM script
Content:
======================
@echo off
c:
cd "C:\SRV\blackfinSVS\srv\"
if exist *.o del /q *.o
if exist *.bin del /q *.bin
if exist *.ldr del /q *.ldr
if exist "C:\SRV\*.ldr" del /q "C:\SRV\*.ldr"
make clean
make
if exist *.o del /q *.o
if exist *.bin del /q *.bin
if not exist "C:\SRV\blackfinSVS\srv\srv1.ldr" goto exit
 
copy "C:\SRV\blackfinSVS\srv\srv1.ldr" "C:\SRV\svs1.ldr"
"C:\Program Files\TTERMPRO\ttpmacro.exe" "C:\SRV\svs1_flash.ttl"
 
:exit
pause
======================
 
 
 
B. "C:\SRV\svs1_flash.ttl"
It makes:
1) show current version info
2) upload to SVS
3) soft reset
4) show new version info
Content:
===================================
connect '192.168.0.34 10001 /B'
if result=0 goto error
 
sendln 'V'
if result=0 goto error
 
sendln 'X'
if result=0 goto error
 
xmodemsend 'C:\SRV\svs1.ldr' 1      
if result=0 goto error
 
if result=1 goto flush
 
; error. stop macro
:error
messagebox 'Error!' 'Tera Term'
end
 
:flush
sendln 'V'
if result=0 goto error
 
sendln 'zZ'
pause 3
 
sendln '$!'
pause 1
 
sendln 'V'
pause 1
 
disconnect
===================================
 
All files can be downloaded from here:
http://81.17.152.8/download/test/svs1.zip
 
Need to change sources path if required and IP.  
I am using 192.168.0.34, you have something else
Only one click at bat file and work done!