У вашего броузера проблема в совместимости с HTML5
Well recently tr_walkway broke because of an update, so this is a quick tutorial on how to spawn your own bots and get it working again!
Here's a list of all the commands in case you missed them in the vid:
sv_cheats 1
mp_autoteambalance 0
mp_teams_unbalance_limit 0
mp_disable_respawn_times 1
tf_bot_add # class team difficulty
tf_bot_melee_only 1
tf_bot_keep_class_after_death 1
tf_bot_kick all (alternatively you can do it by name i.e. "Humans are weak")
bot_dontmove 1