It's difficult to check the code without debugging it.
But if up to 20 pics everything works okay it seems to be a problem of the website. I would try to debug this part of script to find the concrete error line.
some remarks to your code:
The #14# commands are useless as they do nothing in this code.
#PUT#=0#16# is not needed.
#32# changed to #00# as this variable should always be 0 in every script.
changed #COMPUTEVAR# to -1 to use the comparison #IF# #33#==#00# that id used in most scripts.
#POSTER#
#STARTREADWEB#
#PUT#=20#33#
#PUT#=0#00#
:scenasgevivod
#FINDLINE#="sceneThumbnail"#11##ONERROR#=*STOP* //does the same as your code
#FIND#="http://pic.aebn.net/#01##ONERROR#=*STOP* //does the same as your code
#FIND#=g?s#02##ONERROR#=*OK*
#COMPUTECURSOR#=+1 //why this command? it's not needed.
#PUTCURSOR#=#02#
#TAKEWORD#=#16#,#01#,#02#
#TAKEPOSTERFANART#=#16#
#COMPUTEVAR#=#33#-1
#IF# #33#==#00#
#GOTO#=fintheater
#ENDIF#
#GOTO#=scenasgevivod
:fintheater
#ENDPOSTER#
