What is Shradh | श्राद्ध क्या है

Is doing Shradh (Worship of ancestors) the right way of worship?

What does Srimad Bhagavad Gita say about performing shradh?

Saint Rampal ji has given a very thorough analysis of scriptures of Hinduism especially Srimad Bhagavad Gita, Markandeya Puran and Vishnu Puran to answer the above question. 

Srimad Bhagavad Gita Adhyay 9, verse 25 

यान्ति, देवव्रताः, देवान्, पिपर्Úिंन्, यान्ति, पितृव्रताः।
भूतानि,यान्ति,भूतेज्याः,यान्ति, मद्याजिनः,अपि,माम्।।25।।

Worshippers of gods go to gods, worshippers of pitras got to pitras, worshippers of ghosts go to ghosts; likewise, my devotees, who worship in accordance with the scriptures (mataanusaar), also attain me.

Adhyay 16, verse 23-24

यः, शास्त्राविधिम्, उत्सृज्य, वर्तते, कामकारतः,
न, सः, सिद्धिम्, अवाप्नोति, न, सुखम्, न, पराम्, गतिम्।।23।।

तस्मात्, शास्त्राम्, प्रमाणम्, ते, कार्याकार्यव्यवस्थितौ,
ज्ञात्वा, शास्त्राविधानोक्तम्, कर्म, कर्तुम्, इह, अर्हसि।।24।।

He who, abandoning the ordinances of the scriptures, acts whimsically i.e. performs arbitrary way of worship, neither attains happiness, nor is his any task accomplished, and nor attains supreme salvation. Therefore, Arjun, scriptures are the only evidence for the religious practices which should be done and which should not be done in the path of bhakti. One should not accept the path of bhakti, which is against the scriptures, directed by any other particular type of person or saint-sage.

Now see in the evidence in the video below.