What does the mytubeid tag(like <iframe src="/portal/corporateEventsCalendarIframe.html" mytubeid="mytube1" width="820" height="1600" frameborder="0"/>) do in an iframe? 
Note that the iframe do not have an id or as such in it!
How can it be referenced in code? I am using python+selenium+scrapy to build a webscraping tool.
If you want to find  this iframe using selenium try something like
driver.find_element_by_xpath('//iframe[@mytubeid="mytube1"]').
For more explicit answer please provide some code and site url.
Referencing mytubeid in iframe using Python Selenium