I'm sorry, I am not normally one to criticize an OP, but as someone with a finance background, I can't help myself. First off, if you have $100M in interest payments annually, you are well past the point of "falling into debt"....perhaps bankruptcy is the word they are looking for, but you definitely already owe creditors if you are paying interest!
Furthermore, assessing the price paid for the UFC at $4.2B is hard to do without detailed financials; same goes for interest. $100M in annual interest payments is not hard to manage if you have $10B in pretax income; likewise paying $4.2B for the entire organization means nothing without any idea of the adjusted cashflow (money that would otherwise be profit, that can be used to repay interest and debt).
If we go on the assumption that revenue was tracking at approx $600M, with $200M in EBITDA, then I would tend to find the alleged $4.2B price high, personally, however this could depend on a lot of different factors. Are large TV broadcast deals coming up soon? Is there a lucrative Reebok contract inked that we don't know about? Is a big cut to the roster likely to help the bottom line? We don't know.
20X Ebitda is very, very high for an LBO, almost unbankable without leads me to believe there is further information not being shared. Most banks/Subordinated creditors would not be interested in financing a buyout with interest coverage at 2:1 or less, but anything is possible in such a low interest world....