When I checked the altex exchange market link from the OP it doesn't go to a bitcoin market. Altex might have removed that market and moved mint into the litecoin markets.
http://altex.ws/Market/?Pair=MINT/BTCThis link for a MINT/LTC altex market works. The MINT/BTC altex link in the OP should be replaced with this one if there's no altex bitcoin market any longer.
http://altex.ws/Market/Trade/?Pair=MINT/LTCproper link for MINT/BTC trading on altex.ws is
http://altex.ws/Market/trade/?Pair=MINT/BTCit is still active, but thanks for pointing out that the link in the OP is incorrect. I'll ping Ursay to update it