What do you know about bishop Tom Sebastian of the SSCR?  I have recently learned about him, and would like to know what your experience if any has been with him.  I am getting mixed results from my research.  

Never heard of him, but I found this:

http://www.oratoryoftheimmaculata.org/clergy

His episcopal line comes from a bishop Duarte-Costa who was excommunicated in the 40s in Brazil:

http://www.tboyle.net/Catholicism/Costa_Consecrations.html

Msgr. Carlos Duarte Costa was a retired Brazilian diocesan bishop who in 1945 broke with the Roman Catholic Church to found the "Brazilian Apostolic Catholic Church." From him descend scores of independent bishops.

In the 1930s Msgr. Costa was the Brazilian bishop most outspoken in defending the poor. In 1937, at the insistence of the dictatorial Getúlio Vargas régime in Brazil, the Vatican forced Msgr. Costa to retire as Bishop of Botucatu.

Nonetheless, he continued in speaking out on behalf of the poor and, in 1944, was even imprisoned for several months.

Finally, in 1945, after protesting the Vatican's having assisted several nαzιs find refuge in Brazil at the end of World War II, Msgr. Costa broke with Rome and established his own independent church.

Over the next fifteen years, Msgr Costa, along with the first two bishops he consecrated for his new church, helped form in Latin America several other "National Apostolic Catholic Churches." Ultimately there were such churches throughout the Western Hemishere, from Chile to Canada, and even in The Philippines and Australia.

Msgr. Duarte Costa acted as (principal or co-) consecrator for several independent bishops, the first in 1945 and the last, shortly before his death, in 1961.

In the years since his death, however, the few bishops he consecrated have become the source of claimed episcopal orders for a immense number of clergymen (and even women!) saying they are validly consecrated "Catholic" bishops.

....11) Harold Norwood
.........a) John Christopher Simmons
..............I) Daniel Kanyiles
..............II) Thomas Joseph-Francis Patrick Sebastian
..............III) Michael George Charles
....12) Austin Randolph Adler
....13) Randolph Whitcomb Sly
....14) Richard W. Lipka
....15) Philip Charles Zampino
....16) Frederick G. Fick

The Duarte line bishops are, at best, doubtful; they are certainly non-Catholic in the same way the Old Catholics are non-Catholic.

I would stay as far away from Tom Sebastian as I could.

I would take issue with JezusDeKoning's comment, however.  There are a number of Thuc-line bishops as well.  If a bishop hides the source of his consecration, he is likely Duarte-line, but one should not assume this of any independent bishop.

I have met Bishop Thomas in person.

I also attended the conference he had with Father Hesse back in the early 2000s.

Stay away. He will sue any who expose him.

  
 
  Since Costa consecrated after he had been excommunicated, the consecration was not valid and therefore neither is the lineage.

This is absolutely INCORRECT and shows a complete LACK OF UNDERSTANDING of Sacramental Theology. 
If excommunication means that one cannot validly ordain, then how are the Orthodox validly ordained?  
This also implies a belief in the Cyprianic view of Holy Orders versus the Augustinian.  The Cyprianic view is held by the schismatic East and is NOT the teaching of the Catholic Church. 
Do not speak of things of which you do not know. 

Dude.  Breathe.
As I said, I talked the matter over with several bishops and priests, because I don't presume to know sacramental theology.
The unanimous consensus was that the costa line is not Catholic. 

We aren’t talking about whether or not the Duarte-Costa line is Catholic. 
The accusation is that the lineage is not VALID. 
SHOW ME HOW IT IS NOT VALID.  AGAIN THIS IS NOT ABOUT THE CATHOLICTY. 
Am I clear?